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commit 45ab2813d40d88fc575e753c38478de242d03f88 upstream.
If a module fails to add its tracepoints due to module tainting, do not
create the module event infrastructure in the debugfs directory. As the events
will not work and worse yet, they will silently fail, making the user wonder
why the events they enable do not display anything.
Having a warning on module load and the events not visible to the users
will make the cause of the problem much clearer.
Link: http://lkml.kernel.org/r/20140227154923.265882695@goodmis.org
Fixes: 6d723736e472 "tracing/events: add support for modules to TRACE_EVENT"
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d651aa1d68a2f0a7ee65697b04c6a92f8c0a12f2 upstream.
Each sub-buffer (buffer page) has a full 64 bit timestamp. The events on
that page use a 27 bit delta against that timestamp in order to save on
bits written to the ring buffer. If the time between events is larger than
what the 27 bits can hold, a "time extend" event is added to hold the
entire 64 bit timestamp again and the events after that hold a delta from
that timestamp.
As a "time extend" is always paired with an event, it is logical to just
allocate the event with the time extend, to make things a bit more efficient.
Unfortunately, when the pairing code was written, it removed the "delta = 0"
from the first commit on a page, causing the events on the page to be
slightly skewed.
Fixes: 69d1b839f7ee "ring-buffer: Bind time extend and data events together"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 23a8e8441a0a74dd612edf81dc89d1600bc0a3d1 upstream.
Doing some different tests, I discovered that function graph tracing, when
filtered via the set_ftrace_filter and set_ftrace_notrace files, does
not always keep with them if another function ftrace_ops is registered
to trace functions.
The reason is that function graph just happens to trace all functions
that the function tracer enables. When there was only one user of
function tracing, the function graph tracer did not need to worry about
being called by functions that it did not want to trace. But now that there
are other users, this becomes a problem.
For example, one just needs to do the following:
# cd /sys/kernel/debug/tracing
# echo schedule > set_ftrace_filter
# echo function_graph > current_tracer
# cat trace
[..]
0) | schedule() {
------------------------------------------
0) <idle>-0 => rcu_pre-7
------------------------------------------
0) ! 2980.314 us | }
0) | schedule() {
------------------------------------------
0) rcu_pre-7 => <idle>-0
------------------------------------------
0) + 20.701 us | }
# echo 1 > /proc/sys/kernel/stack_tracer_enabled
# cat trace
[..]
1) + 20.825 us | }
1) + 21.651 us | }
1) + 30.924 us | } /* SyS_ioctl */
1) | do_page_fault() {
1) | __do_page_fault() {
1) 0.274 us | down_read_trylock();
1) 0.098 us | find_vma();
1) | handle_mm_fault() {
1) | _raw_spin_lock() {
1) 0.102 us | preempt_count_add();
1) 0.097 us | do_raw_spin_lock();
1) 2.173 us | }
1) | do_wp_page() {
1) 0.079 us | vm_normal_page();
1) 0.086 us | reuse_swap_page();
1) 0.076 us | page_move_anon_rmap();
1) | unlock_page() {
1) 0.082 us | page_waitqueue();
1) 0.086 us | __wake_up_bit();
1) 1.801 us | }
1) 0.075 us | ptep_set_access_flags();
1) | _raw_spin_unlock() {
1) 0.098 us | do_raw_spin_unlock();
1) 0.105 us | preempt_count_sub();
1) 1.884 us | }
1) 9.149 us | }
1) + 13.083 us | }
1) 0.146 us | up_read();
When the stack tracer was enabled, it enabled all functions to be traced, which
now the function graph tracer also traces. This is a side effect that should
not occur.
To fix this a test is added when the function tracing is changed, as well as when
the graph tracer is enabled, to see if anything other than the ftrace global_ops
function tracer is enabled. If so, then the graph tracer calls a test trampoline
that will look at the function that is being traced and compare it with the
filters defined by the global_ops.
As an optimization, if there's no other function tracers registered, or if
the only registered function tracers also use the global ops, the function
graph infrastructure will call the registered function graph callback directly
and not go through the test trampoline.
Fixes: d2d45c7a03a2 "tracing: Have stack_tracer use a separate list of functions"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit a4c35ed241129dd142be4cadb1e5a474a56d5464 upstream.
The synchronization needed after ftrace_ops are unregistered must happen
after the callback is disabled from becing called by functions.
The current location happens after the function is being removed from the
internal lists, but not after the function callbacks were disabled, leaving
the functions susceptible of being called after their callbacks are freed.
This affects perf and any externel users of function tracing (LTTng and
SystemTap).
Fixes: cdbe61bfe704 "ftrace: Allow dynamically allocated function tracers"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 405e1d834807e51b2ebd3dea81cb51e53fb61504 upstream.
ftrace_trace_function is a variable that holds what function will be called
directly by the assembly code (mcount). If just a single function is
registered and it handles recursion itself, then the assembly will call that
function directly without any helper function. It also passes in the
ftrace_op that was registered with the callback. The ftrace_op to send is
stored in the function_trace_op variable.
The ftrace_trace_function and function_trace_op needs to be coordinated such
that the called callback wont be called with the wrong ftrace_op, otherwise
bad things can happen if it expected a different op. Luckily, there's no
callback that doesn't use the helper functions that requires this. But
there soon will be and this needs to be fixed.
Use a set_function_trace_op to store the ftrace_op to set the
function_trace_op to when it is safe to do so (during the update function
within the breakpoint or stop machine calls). Or if dynamic ftrace is not
being used (static tracing) then we have to do a bit more synchronization
when the ftrace_trace_function is set as that takes affect immediately
(as oppose to dynamic ftrace doing it with the modification of the trampoline).
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 3132e107d608f8753240d82d61303c500fd515b4 upstream.
If trace_puts() is used very early in boot up, it can crash the machine
if it is called before the ring buffer is allocated. If a trace_printk()
is used with no arguments, then it will be converted into a trace_puts()
and suffer the same fate.
Fixes: 09ae72348ecc "tracing: Add trace_puts() for even faster trace_printk() tracing"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit dced341b2d4f06668efaab33f88de5d287c0f45b upstream.
The trace buffer has a descriptor pointer that goes back to the trace
array. But it was never assigned. Luckily, nothing uses it (yet), but
it will in the future.
Although nothing currently uses this, if any of the new features get
backported to older kernels, and because this is such a simple change,
I'm marking it for stable too.
Fixes: 12883efb670c "tracing: Consolidate max_tr into main trace_array structure"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit c4602c1c818bd6626178d6d3fcc152d9f2f48ac0 upstream.
Ftrace currently initializes only the online CPUs. This implementation has
two problems:
- If we online a CPU after we enable the function profile, and then run the
test, we will lose the trace information on that CPU.
Steps to reproduce:
# echo 0 > /sys/devices/system/cpu/cpu1/online
# cd <debugfs>/tracing/
# echo <some function name> >> set_ftrace_filter
# echo 1 > function_profile_enabled
# echo 1 > /sys/devices/system/cpu/cpu1/online
# run test
- If we offline a CPU before we enable the function profile, we will not clear
the trace information when we enable the function profile. It will trouble
the users.
Steps to reproduce:
# cd <debugfs>/tracing/
# echo <some function name> >> set_ftrace_filter
# echo 1 > function_profile_enabled
# run test
# cat trace_stat/function*
# echo 0 > /sys/devices/system/cpu/cpu1/online
# echo 0 > function_profile_enabled
# echo 1 > function_profile_enabled
# cat trace_stat/function*
# run test
# cat trace_stat/function*
So it is better that we initialize the ftrace profiler for each possible cpu
every time we enable the function profile instead of just the online ones.
Link: http://lkml.kernel.org/r/1387178401-10619-1-git-send-email-miaox@cn.fujitsu.com
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8a56d7761d2d041ae5e8215d20b4167d8aa93f51 upstream.
Commit 8c4f3c3fa9681 "ftrace: Check module functions being traced on reload"
fixed module loading and unloading with respect to function tracing, but
it missed the function graph tracer. If you perform the following
# cd /sys/kernel/debug/tracing
# echo function_graph > current_tracer
# modprobe nfsd
# echo nop > current_tracer
You'll get the following oops message:
------------[ cut here ]------------
WARNING: CPU: 2 PID: 2910 at /linux.git/kernel/trace/ftrace.c:1640 __ftrace_hash_rec_update.part.35+0x168/0x1b9()
Modules linked in: nfsd exportfs nfs_acl lockd ipt_MASQUERADE sunrpc ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables uinput snd_hda_codec_idt
CPU: 2 PID: 2910 Comm: bash Not tainted 3.13.0-rc1-test #7
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
0000000000000668 ffff8800787efcf8 ffffffff814fe193 ffff88007d500000
0000000000000000 ffff8800787efd38 ffffffff8103b80a 0000000000000668
ffffffff810b2b9a ffffffff81a48370 0000000000000001 ffff880037aea000
Call Trace:
[<ffffffff814fe193>] dump_stack+0x4f/0x7c
[<ffffffff8103b80a>] warn_slowpath_common+0x81/0x9b
[<ffffffff810b2b9a>] ? __ftrace_hash_rec_update.part.35+0x168/0x1b9
[<ffffffff8103b83e>] warn_slowpath_null+0x1a/0x1c
[<ffffffff810b2b9a>] __ftrace_hash_rec_update.part.35+0x168/0x1b9
[<ffffffff81502f89>] ? __mutex_lock_slowpath+0x364/0x364
[<ffffffff810b2cc2>] ftrace_shutdown+0xd7/0x12b
[<ffffffff810b47f0>] unregister_ftrace_graph+0x49/0x78
[<ffffffff810c4b30>] graph_trace_reset+0xe/0x10
[<ffffffff810bf393>] tracing_set_tracer+0xa7/0x26a
[<ffffffff810bf5e1>] tracing_set_trace_write+0x8b/0xbd
[<ffffffff810c501c>] ? ftrace_return_to_handler+0xb2/0xde
[<ffffffff811240a8>] ? __sb_end_write+0x5e/0x5e
[<ffffffff81122aed>] vfs_write+0xab/0xf6
[<ffffffff8150a185>] ftrace_graph_caller+0x85/0x85
[<ffffffff81122dbd>] SyS_write+0x59/0x82
[<ffffffff8150a185>] ftrace_graph_caller+0x85/0x85
[<ffffffff8150a2d2>] system_call_fastpath+0x16/0x1b
---[ end trace 940358030751eafb ]---
The above mentioned commit didn't go far enough. Well, it covered the
function tracer by adding checks in __register_ftrace_function(). The
problem is that the function graph tracer circumvents that (for a slight
efficiency gain when function graph trace is running with a function
tracer. The gain was not worth this).
The problem came with ftrace_startup() which should always be called after
__register_ftrace_function(), if you want this bug to be completely fixed.
Anyway, this solution moves __register_ftrace_function() inside of
ftrace_startup() and removes the need to call them both.
Reported-by: Dave Wysochanski <dwysocha@redhat.com>
Fixes: ed926f9b35cd ("ftrace: Use counters to enable functions to trace")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 12ae030d54ef250706da5642fc7697cc60ad0df7 upstream.
The current default perf paranoid level is "1" which has
"perf_paranoid_kernel()" return false, and giving any operations that
use it, access to normal users. Unfortunately, this includes function
tracing and normal users should not be allowed to enable function
tracing by default.
The proper level is defined at "-1" (full perf access), which
"perf_paranoid_tracepoint_raw()" will only give access to. Use that
check instead for enabling function tracing.
Reported-by: Dave Jones <davej@redhat.com>
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
CVE: CVE-2013-2930
Fixes: ced39002f5ea ("ftrace, perf: Add support to use function tracepoint in perf")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 057db8488b53d5e4faa0cedb2f39d4ae75dfbdbb upstream.
Andrey reported the following report:
ERROR: AddressSanitizer: heap-buffer-overflow on address ffff8800359c99f3
ffff8800359c99f3 is located 0 bytes to the right of 243-byte region [ffff8800359c9900, ffff8800359c99f3)
Accessed by thread T13003:
#0 ffffffff810dd2da (asan_report_error+0x32a/0x440)
#1 ffffffff810dc6b0 (asan_check_region+0x30/0x40)
#2 ffffffff810dd4d3 (__tsan_write1+0x13/0x20)
#3 ffffffff811cd19e (ftrace_regex_release+0x1be/0x260)
#4 ffffffff812a1065 (__fput+0x155/0x360)
#5 ffffffff812a12de (____fput+0x1e/0x30)
#6 ffffffff8111708d (task_work_run+0x10d/0x140)
#7 ffffffff810ea043 (do_exit+0x433/0x11f0)
#8 ffffffff810eaee4 (do_group_exit+0x84/0x130)
#9 ffffffff810eafb1 (SyS_exit_group+0x21/0x30)
#10 ffffffff81928782 (system_call_fastpath+0x16/0x1b)
Allocated by thread T5167:
#0 ffffffff810dc778 (asan_slab_alloc+0x48/0xc0)
#1 ffffffff8128337c (__kmalloc+0xbc/0x500)
#2 ffffffff811d9d54 (trace_parser_get_init+0x34/0x90)
#3 ffffffff811cd7b3 (ftrace_regex_open+0x83/0x2e0)
#4 ffffffff811cda7d (ftrace_filter_open+0x2d/0x40)
#5 ffffffff8129b4ff (do_dentry_open+0x32f/0x430)
#6 ffffffff8129b668 (finish_open+0x68/0xa0)
#7 ffffffff812b66ac (do_last+0xb8c/0x1710)
#8 ffffffff812b7350 (path_openat+0x120/0xb50)
#9 ffffffff812b8884 (do_filp_open+0x54/0xb0)
#10 ffffffff8129d36c (do_sys_open+0x1ac/0x2c0)
#11 ffffffff8129d4b7 (SyS_open+0x37/0x50)
#12 ffffffff81928782 (system_call_fastpath+0x16/0x1b)
Shadow bytes around the buggy address:
ffff8800359c9700: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
ffff8800359c9780: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa
ffff8800359c9800: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
ffff8800359c9880: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
ffff8800359c9900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>ffff8800359c9980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00[03]fb
ffff8800359c9a00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
ffff8800359c9a80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
ffff8800359c9b00: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
ffff8800359c9b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8800359c9c00: 00 00 00 00 00 00 00 00 fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap redzone: fa
Heap kmalloc redzone: fb
Freed heap region: fd
Shadow gap: fe
The out-of-bounds access happens on 'parser->buffer[parser->idx] = 0;'
Although the crash happened in ftrace_regex_open() the real bug
occurred in trace_get_user() where there's an incrementation to
parser->idx without a check against the size. The way it is triggered
is if userspace sends in 128 characters (EVENT_BUF_SIZE + 1), the loop
that reads the last character stores it and then breaks out because
there is no more characters. Then the last character is read to determine
what to do next, and the index is incremented without checking size.
Then the caller of trace_get_user() usually nulls out the last character
with a zero, but since the index is equal to the size, it writes a nul
character after the allocated space, which can corrupt memory.
Luckily, only root user has write access to this file.
Link: http://lkml.kernel.org/r/20131009222323.04fd1a0d@gandalf.local.home
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8c4f3c3fa9681dc549cd35419b259496082fef8b upstream.
There's been a nasty bug that would show up and not give much info.
The bug displayed the following warning:
WARNING: at kernel/trace/ftrace.c:1529 __ftrace_hash_rec_update+0x1e3/0x230()
Pid: 20903, comm: bash Tainted: G O 3.6.11+ #38405.trunk
Call Trace:
[<ffffffff8103e5ff>] warn_slowpath_common+0x7f/0xc0
[<ffffffff8103e65a>] warn_slowpath_null+0x1a/0x20
[<ffffffff810c2ee3>] __ftrace_hash_rec_update+0x1e3/0x230
[<ffffffff810c4f28>] ftrace_hash_move+0x28/0x1d0
[<ffffffff811401cc>] ? kfree+0x2c/0x110
[<ffffffff810c68ee>] ftrace_regex_release+0x8e/0x150
[<ffffffff81149f1e>] __fput+0xae/0x220
[<ffffffff8114a09e>] ____fput+0xe/0x10
[<ffffffff8105fa22>] task_work_run+0x72/0x90
[<ffffffff810028ec>] do_notify_resume+0x6c/0xc0
[<ffffffff8126596e>] ? trace_hardirqs_on_thunk+0x3a/0x3c
[<ffffffff815c0f88>] int_signal+0x12/0x17
---[ end trace 793179526ee09b2c ]---
It was finally narrowed down to unloading a module that was being traced.
It was actually more than that. When functions are being traced, there's
a table of all functions that have a ref count of the number of active
tracers attached to that function. When a function trace callback is
registered to a function, the function's record ref count is incremented.
When it is unregistered, the function's record ref count is decremented.
If an inconsistency is detected (ref count goes below zero) the above
warning is shown and the function tracing is permanently disabled until
reboot.
The ftrace callback ops holds a hash of functions that it filters on
(and/or filters off). If the hash is empty, the default means to filter
all functions (for the filter_hash) or to disable no functions (for the
notrace_hash).
When a module is unloaded, it frees the function records that represent
the module functions. These records exist on their own pages, that is
function records for one module will not exist on the same page as
function records for other modules or even the core kernel.
Now when a module unloads, the records that represents its functions are
freed. When the module is loaded again, the records are recreated with
a default ref count of zero (unless there's a callback that traces all
functions, then they will also be traced, and the ref count will be
incremented).
The problem is that if an ftrace callback hash includes functions of the
module being unloaded, those hash entries will not be removed. If the
module is reloaded in the same location, the hash entries still point
to the functions of the module but the module's ref counts do not reflect
that.
With the help of Steve and Joern, we found a reproducer:
Using uinput module and uinput_release function.
cd /sys/kernel/debug/tracing
modprobe uinput
echo uinput_release > set_ftrace_filter
echo function > current_tracer
rmmod uinput
modprobe uinput
# check /proc/modules to see if loaded in same addr, otherwise try again
echo nop > current_tracer
[BOOM]
The above loads the uinput module, which creates a table of functions that
can be traced within the module.
We add uinput_release to the filter_hash to trace just that function.
Enable function tracincg, which increments the ref count of the record
associated to uinput_release.
Remove uinput, which frees the records including the one that represents
uinput_release.
Load the uinput module again (and make sure it's at the same address).
This recreates the function records all with a ref count of zero,
including uinput_release.
Disable function tracing, which will decrement the ref count for uinput_release
which is now zero because of the module removal and reload, and we have
a mismatch (below zero ref count).
The solution is to check all currently tracing ftrace callbacks to see if any
are tracing any of the module's functions when a module is loaded (it already does
that with callbacks that trace all functions). If a callback happens to have
a module function being traced, it increments that records ref count and starts
tracing that function.
There may be a strange side effect with this, where tracing module functions
on unload and then reloading a new module may have that new module's functions
being traced. This may be something that confuses the user, but it's not
a big deal. Another approach is to disable all callback hashes on module unload,
but this leaves some ftrace callbacks that may not be registered, but can
still have hashes tracing the module's function where ftrace doesn't know about
it. That situation can cause the same bug. This solution solves that case too.
Another benefit of this solution, is it is possible to trace a module's
function on unload and load.
Link: http://lkml.kernel.org/r/20130705142629.GA325@redhat.com
Reported-by: Jörn Engel <joern@logfs.org>
Reported-by: Dave Jones <davej@redhat.com>
Reported-by: Steve Hodgson <steve@purestorage.com>
Tested-by: Steve Hodgson <steve@purestorage.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit c6c2401d8bbaf9edc189b4c35a8cb2780b8b988e upstream.
Uprobes suffer the same problem that kprobes have. There's a race between
writing to the "enable" file and removing the probe. The probe checks for
it being in use and if it is not, goes about deleting the probe and the
event that represents it. But the problem with that is, after it checks
if it is in use it can be enabled, and the deletion of the event (access
to the probe) will fail, as it is in use. But the uprobe will still be
deleted. This is a problem as the event can reference the uprobe that
was deleted.
The fix is to remove the event first, and check to make sure the event
removal succeeds. Then it is safe to remove the probe.
When the event exists, either ftrace or perf can enable the probe and
prevent the event from being removed.
Link: http://lkml.kernel.org/r/20130704034038.991525256@goodmis.org
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 40c32592668b727cbfcf7b1c0567f581bd62a5e4 upstream.
When a probe is being removed, it cleans up the event files that correspond
to the probe. But there is a race between writing to one of these files
and deleting the probe. This is especially true for the "enable" file.
CPU 0 CPU 1
----- -----
fd = open("enable",O_WRONLY);
probes_open()
release_all_trace_probes()
unregister_trace_probe()
if (trace_probe_is_enabled(tp))
return -EBUSY
write(fd, "1", 1)
__ftrace_set_clr_event()
call->class->reg()
(kprobe_register)
enable_trace_probe(tp)
__unregister_trace_probe(tp);
list_del(&tp->list)
unregister_probe_event(tp) <-- fails!
free_trace_probe(tp)
write(fd, "0", 1)
__ftrace_set_clr_event()
call->class->unreg
(kprobe_register)
disable_trace_probe(tp) <-- BOOM!
A test program was written that used two threads to simulate the
above scenario adding a nanosleep() interval to change the timings
and after several thousand runs, it was able to trigger this bug
and crash:
BUG: unable to handle kernel paging request at 00000005000000f9
IP: [<ffffffff810dee70>] probes_open+0x3b/0xa7
PGD 7808a067 PUD 0
Oops: 0000 [#1] PREEMPT SMP
Dumping ftrace buffer:
---------------------------------
Modules linked in: ipt_MASQUERADE sunrpc ip6t_REJECT nf_conntrack_ipv6
CPU: 1 PID: 2070 Comm: test-kprobe-rem Not tainted 3.11.0-rc3-test+ #47
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
task: ffff880077756440 ti: ffff880076e52000 task.ti: ffff880076e52000
RIP: 0010:[<ffffffff810dee70>] [<ffffffff810dee70>] probes_open+0x3b/0xa7
RSP: 0018:ffff880076e53c38 EFLAGS: 00010203
RAX: 0000000500000001 RBX: ffff88007844f440 RCX: 0000000000000003
RDX: 0000000000000003 RSI: 0000000000000003 RDI: ffff880076e52000
RBP: ffff880076e53c58 R08: ffff880076e53bd8 R09: 0000000000000000
R10: ffff880077756440 R11: 0000000000000006 R12: ffffffff810dee35
R13: ffff880079250418 R14: 0000000000000000 R15: ffff88007844f450
FS: 00007f87a276f700(0000) GS:ffff88007d480000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000005000000f9 CR3: 0000000077262000 CR4: 00000000000007e0
Stack:
ffff880076e53c58 ffffffff81219ea0 ffff88007844f440 ffffffff810dee35
ffff880076e53ca8 ffffffff81130f78 ffff8800772986c0 ffff8800796f93a0
ffffffff81d1b5d8 ffff880076e53e04 0000000000000000 ffff88007844f440
Call Trace:
[<ffffffff81219ea0>] ? security_file_open+0x2c/0x30
[<ffffffff810dee35>] ? unregister_trace_probe+0x4b/0x4b
[<ffffffff81130f78>] do_dentry_open+0x162/0x226
[<ffffffff81131186>] finish_open+0x46/0x54
[<ffffffff8113f30b>] do_last+0x7f6/0x996
[<ffffffff8113cc6f>] ? inode_permission+0x42/0x44
[<ffffffff8113f6dd>] path_openat+0x232/0x496
[<ffffffff8113fc30>] do_filp_open+0x3a/0x8a
[<ffffffff8114ab32>] ? __alloc_fd+0x168/0x17a
[<ffffffff81131f4e>] do_sys_open+0x70/0x102
[<ffffffff8108f06e>] ? trace_hardirqs_on_caller+0x160/0x197
[<ffffffff81131ffe>] SyS_open+0x1e/0x20
[<ffffffff81522742>] system_call_fastpath+0x16/0x1b
Code: e5 41 54 53 48 89 f3 48 83 ec 10 48 23 56 78 48 39 c2 75 6c 31 f6 48 c7
RIP [<ffffffff810dee70>] probes_open+0x3b/0xa7
RSP <ffff880076e53c38>
CR2: 00000005000000f9
---[ end trace 35f17d68fc569897 ]---
The unregister_trace_probe() must be done first, and if it fails it must
fail the removal of the kprobe.
Several changes have already been made by Oleg Nesterov and Masami Hiramatsu
to allow moving the unregister_probe_event() before the removal of
the probe and exit the function if it fails. This prevents the tp
structure from being used after it is freed.
Link: http://lkml.kernel.org/r/20130704034038.819592356@goodmis.org
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 2816c551c796ec14620325b2c9ed75b9979d3125 upstream.
Change trace_remove_event_call(call) to return the error if this
call is active. This is what the callers assume but can't verify
outside of the tracing locks. Both trace_kprobe.c/trace_uprobe.c
need the additional changes, unregister_trace_probe() should abort
if trace_remove_event_call() fails.
The caller is going to free this call/file so we must ensure that
nobody can use them after trace_remove_event_call() succeeds.
debugfs should be fine after the previous changes and event_remove()
does TRACE_REG_UNREGISTER, but still there are 2 reasons why we need
the additional checks:
- There could be a perf_event(s) attached to this tp_event, so the
patch checks ->perf_refcount.
- TRACE_REG_UNREGISTER can be suppressed by FTRACE_EVENT_FL_SOFT_MODE,
so we simply check FTRACE_EVENT_FL_ENABLED protected by event_mutex.
Link: http://lkml.kernel.org/r/20130729175033.GB26284@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit bf682c3159c4d298d1126a56793ed3f5e80395f7 upstream.
Change remove_event_file_dir() to clear ->i_private for every
file we are going to remove.
We need to check file->dir != NULL because event_create_dir()
can fail. debugfs_remove_recursive(NULL) is fine but the patch
moves it under the same check anyway for readability.
spin_lock(d_lock) and "d_inode != NULL" check are not needed
afaics, but I do not understand this code enough.
tracing_open_generic_file() and tracing_release_generic_file()
can go away, ftrace_enable_fops and ftrace_event_filter_fops()
use tracing_open_generic() but only to check tracing_disabled.
This fixes all races with event_remove() or instance_delete().
f_op->read/write/whatever can never use the freed file/call,
all event/* files were changed to check and use ->i_private
under event_mutex.
Note: this doesn't not fix other problems, event_remove() can
destroy the active ftrace_event_call, we need more changes but
those changes are completely orthogonal.
Link: http://lkml.kernel.org/r/20130728183527.GB16723@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f6a84bdc75b5c11621dec58db73fe102cbaf40cc upstream.
Preparation for the next patch. Extract the common code from
remove_event_from_tracers() and __trace_remove_event_dirs()
into the new helper, remove_event_file_dir().
The patch looks more complicated than it actually is, it also
moves remove_subsystem() up to avoid the forward declaration.
Link: http://lkml.kernel.org/r/20130726172547.GA3629@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit c5a44a1200c6eda2202434f25325e8ad19533fca upstream.
trace_format_open() and trace_format_seq_ops are racy, nothing
protects ftrace_event_call from trace_remove_event_call().
Change f_start() to take event_mutex and verify i_private != NULL,
change f_stop() to drop this lock.
This fixes nothing, but now we can change debugfs_remove("format")
callers to nullify ->i_private and fix the the problem.
Note: the usage of event_mutex is sub-optimal but simple, we can
change this later.
Link: http://lkml.kernel.org/r/20130726172543.GA3622@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit e2912b091c26b8ea95e5e00a43a7ac620f6c94a6 upstream.
event_filter_read/write() are racy, ftrace_event_call can be already
freed by trace_remove_event_call() callers.
1. Shift mutex_lock(event_mutex) from print/apply_event_filter to
the callers.
2. Change the callers, event_filter_read() and event_filter_write()
to read i_private under this mutex and abort if it is NULL.
This fixes nothing, but now we can change debugfs_remove("filter")
callers to nullify ->i_private and fix the the problem.
Link: http://lkml.kernel.org/r/20130726172540.GA3619@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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|
commit bc6f6b08dee5645770efb4b76186ded313f23752 upstream.
tracing_open_generic_file() is racy, ftrace_event_file can be
already freed by rmdir or trace_remove_event_call().
Change event_enable_read() and event_disable_read() to read and
verify "file = i_private" under event_mutex.
This fixes nothing, but now we can change debugfs_remove("enable")
callers to nullify ->i_private and fix the the problem.
Link: http://lkml.kernel.org/r/20130726172536.GA3612@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1a11126bcb7c93c289bf3218fa546fd3b0c0df8b upstream.
event_id_read() is racy, ftrace_event_call can be already freed
by trace_remove_event_call() callers.
Change event_create_dir() to pass "data = call->event.type", this
is all event_id_read() needs. ftrace_event_id_fops no longer needs
tracing_open_generic().
We add the new helper, event_file_data(), to read ->i_private, it
will have more users.
Note: currently ACCESS_ONCE() and "id != 0" check are not needed,
but we are going to change event_remove/rmdir to clear ->i_private.
Link: http://lkml.kernel.org/r/20130726172532.GA3605@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 195a8afc7ac962f8da795549fe38e825f1372b0d upstream.
If a ftrace ops is registered with the SAVE_REGS flag set, and there's
already a ops registered to one of its functions but without the
SAVE_REGS flag, there's a small race window where the SAVE_REGS ops gets
added to the list of callbacks to call for that function before the
callback trampoline gets set to save the regs.
The problem is, the function is not currently saving regs, which opens
a small race window where the ops that is expecting regs to be passed
to it, wont. This can cause a crash if the callback were to reference
the regs, as the SAVE_REGS guarantees that regs will be set.
To fix this, we add a check in the loop case where it checks if the ops
has the SAVE_REGS flag set, and if so, it will ignore it if regs is
not set.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 6484c71cbc170634fa131b6d022d86d61686b88b upstream.
tracing_open() and tracing_snapshot_open() are racy, the memory
inode->i_private points to can be already freed.
Convert these last users of "inode->i_private == trace_cpu" to
use "i_private = trace_array" and rely on tracing_get_cpu().
v2: incorporate the fix from Steven, tracing_release() must not
blindly dereference file->private_data unless we know that
the file was opened for reading.
Link: http://lkml.kernel.org/r/20130723152610.GA23737@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 0bc392ee46d0fd8e6b678457ef71f074f19a03c5 upstream.
tracing_open_generic_tc() is racy, the memory inode->i_private
points to can be already freed.
1. Change its last user, tracing_entries_fops, to use
tracing_*_generic_tr() instead.
2. Change debugfs_create_file("buffer_size_kb", data) callers
to pass "data = tr".
3. Change tracing_entries_read() and tracing_entries_write() to
use tracing_get_cpu().
4. Kill the no longer used tracing_open_generic_tc() and
tracing_release_generic_tc().
Link: http://lkml.kernel.org/r/20130723152606.GA23730@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 4d3435b8a4c3357695e09c5e7a3bf73a19fca5b0 upstream.
tracing_open_generic_tc() is racy, the memory inode->i_private
points to can be already freed.
1. Change one of its users, tracing_stats_fops, to use
tracing_*_generic_tr() instead.
2. Change trace_create_cpu_file("stats", data) to pass "data = tr".
3. Change tracing_stats_read() to use tracing_get_cpu().
Link: http://lkml.kernel.org/r/20130723152603.GA23727@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 46ef2be0d1d5ccea0c41bb606143586daadd537c upstream.
tracing_buffers_open() is racy, the memory inode->i_private points
to can be already freed.
Change debugfs_create_file("trace_pipe_raw", data) caller to pass
"data = tr", tracing_buffers_open() can use tracing_get_cpu().
Change debugfs_create_file("snapshot_raw_fops", data) caller too,
this file uses tracing_buffers_open/release.
Link: http://lkml.kernel.org/r/20130723152600.GA23720@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 15544209cb0b5312e5220a9337a1fe61d1a1f2d9 upstream.
tracing_open_pipe() is racy, the memory inode->i_private points to
can be already freed.
Change debugfs_create_file("trace_pipe", data) callers to to pass
"data = tr", tracing_open_pipe() can use tracing_get_cpu().
Link: http://lkml.kernel.org/r/20130723152557.GA23717@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 649e9c70da6bfbeb563193a35d3424a5aa7c0d38 upstream.
Every "file_operations" used by tracing_init_debugfs_percpu is buggy.
f_op->open/etc does:
1. struct trace_cpu *tc = inode->i_private;
struct trace_array *tr = tc->tr;
2. trace_array_get(tr) or fail;
3. do_something(tc);
But tc (and tr) can be already freed before trace_array_get() is called.
And it doesn't matter whether this file is per-cpu or it was created by
init_tracer_debugfs(), free_percpu() or kfree() are equally bad.
Note that even 1. is not safe, the freed memory can be unmapped. But even
if it was safe trace_array_get() can wrongly succeed if we also race with
the next new_instance_create() which can re-allocate the same tr, or tc
was overwritten and ->tr points to the valid tr. In this case 3. uses the
freed/reused memory.
Add the new trivial helper, trace_create_cpu_file() which simply calls
trace_create_file() and encodes "cpu" in "struct inode". Another helper,
tracing_get_cpu() will be used to read cpu_nr-or-RING_BUFFER_ALL_CPUS.
The patch abuses ->i_cdev to encode the number, it is never used unless
the file is S_ISCHR(). But we could use something else, say, i_bytes or
even ->d_fsdata. In any case this hack is hidden inside these 2 helpers,
it would be trivial to change them if needed.
This patch only changes tracing_init_debugfs_percpu() to use the new
trace_create_cpu_file(), the next patches will change file_operations.
Note: tracing_get_cpu(inode) is always safe but you can't trust the
result unless trace_array_get() was called, without trace_types_lock
which acts as a barrier it can wrongly return RING_BUFFER_ALL_CPUS.
Link: http://lkml.kernel.org/r/20130723152554.GA23710@redhat.com
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit a232e270dcb55a70ad3241bc6fc160fd9b5c9e6c upstream.
Wait for disabling all running kprobe handlers when a kprobe
event is disabled, since the caller, trace_remove_event_call()
supposes that a removing event is disabled completely by
disabling the event.
With this change, ftrace can ensure that there is no running
event handlers after disabling it.
Link: http://lkml.kernel.org/r/20130709093526.20138.93100.stgit@mhiramat-M0-7522
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit aaf6ac0f0871cb7fc0f28f3a00edf329bc7adc29 upstream.
There's no point calling it when _alloc() failed.
Link: http://lkml.kernel.org/r/1370585268-29169-1-git-send-email-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 9457158bbc0ee04ecef76862d73eecd8076e9c7b upstream.
Fixed two issues with changing the timestamp clock with trace_clock:
- The global buffer was reset on instance clock changes. Change this to pass
the correct per-instance buffer
- ftrace_now() is used to set buf->time_start in tracing_reset_online_cpus().
This was incorrect because ftrace_now() used the global buffer's clock to
return the current time. Change this to use buffer_ftrace_now() which
returns the current time for the correct per-instance buffer.
Also removed tracing_reset_current() because it is not used anywhere
Link: http://lkml.kernel.org/r/1375493777-17261-2-git-send-email-azl@google.com
Signed-off-by: Alexander Z Lam <azl@google.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 10246fa35d4ffdfe472185d4cbf9c2dfd9a9f023 upstream.
If the ring buffer is disabled and the irqsoff tracer records a trace it
will clear out its buffer and lose the data it had previously recorded.
Currently there's a callback when writing to the tracing_of file, but if
tracing is disabled via the function tracer trigger, it will not inform
the irqsoff tracer to stop recording.
By using the "mirror" flag (buffer_disabled) in the trace_array, that keeps
track of the status of the trace_array's buffer, it gives the irqsoff
tracer a fast way to know if it should record a new trace or not.
The flag may be a little behind the real state of the buffer, but it
should not affect the trace too much. It's more important for the irqsoff
tracer to be fast.
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 711e124379e0f889e40e2f01d7f5d61936d3cd23 upstream.
Releasing the free_buffer file in an instance causes the global buffer
to be stopped when TRACE_ITER_STOP_ON_FREE is enabled. Operate on the
correct buffer.
Link: http://lkml.kernel.org/r/1375493777-17261-1-git-send-email-azl@google.com
Signed-off-by: Alexander Z Lam <azl@google.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ed5467da0e369e65b247b99eb6403cb79172bcda upstream.
tracing_read_pipe zeros all fields bellow "seq". The declaration contains
a comment about that, but it doesn't help.
The first field is "snapshot", it's true when current open file is
snapshot. Looks obvious, that it should not be zeroed.
The second field is "started". It was converted from cpumask_t to
cpumask_var_t (v2.6.28-4983-g4462344), in other words it was
converted from cpumask to pointer on cpumask.
Currently the reference on "started" memory is lost after the first read
from tracing_read_pipe and a proper object will never be freed.
The "started" is never dereferenced for trace_pipe, because trace_pipe
can't have the TRACE_FILE_ANNOTATE options.
Link: http://lkml.kernel.org/r/1375463803-3085183-1-git-send-email-avagin@openvz.org
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 09d8091c024ec88d1541d93eb8ddb2bd5cf10c39 upstream.
Commit a82274151af "tracing: Protect ftrace_trace_arrays list in trace_events.c"
added taking the trace_types_lock mutex in trace_events.c as there were
several locations that needed it for protection. Unfortunately, it also
encapsulated a call to tracing_reset_all_online_cpus() which also takes
the trace_types_lock, causing a deadlock.
This happens when a module has tracepoints and has been traced. When the
module is removed, the trace events module notifier will grab the
trace_types_lock, do a bunch of clean ups, and also clears the buffer
by calling tracing_reset_all_online_cpus. This doesn't happen often
which explains why it wasn't caught right away.
Commit a82274151af was marked for stable, which means this must be
sent to stable too.
Link: http://lkml.kernel.org/r/51EEC646.7070306@broadcom.com
Reported-by: Arend van Spril <arend@broadcom.com>
Tested-by: Arend van Spriel <arend@broadcom.com>
Cc: Alexander Z Lam <azl@google.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit e70e78e3c83b536730e31231dd9b979768d8df3c upstream.
tracing_buffers_open() does trace_array_get() and then it wrongly
inrcements tr->ref again under trace_types_lock. This means that
every caller leaks trace_array:
# cd /sys/kernel/debug/tracing/
# mkdir instances/X
# true < instances/X/per_cpu/cpu0/trace_pipe_raw
# rmdir instances/X
rmdir: failed to remove `instances/X': Device or resource busy
Link: http://lkml.kernel.org/r/20130719153644.GA18899@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f77d09a384676bde6445413949d9d2c508ff3e62 upstream.
Some error paths did not handle ref counting properly, and some trace files need
ref counting.
Link: http://lkml.kernel.org/r/1374171524-11948-1-git-send-email-azl@google.com
Signed-off-by: Alexander Z Lam <azl@google.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 609e85a70bcd0eedf4ec60639dbcfb1ab011e054 upstream.
Remove debugfs directories for tracing instances during creation if an error
occurs causing the trace_array for that instance to not be added to
ftrace_trace_arrays. If the directory continues to exist after the error, it
cannot be removed because the respective trace_array is not in
ftrace_trace_arrays.
Link: http://lkml.kernel.org/r/1373502874-1706-2-git-send-email-azl@google.com
Signed-off-by: Alexander Z Lam <azl@google.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8e2e2fa47129532a30cff6c25a47078dc97d9260 upstream.
Commit a695cb58162 "tracing: Prevent deleting instances when they are being read"
tried to fix a race between deleting a trace instance and reading contents
of a trace file. But it wasn't good enough. The following could crash the kernel:
# cd /sys/kernel/debug/tracing/instances
# ( while :; do mkdir foo; rmdir foo; done ) &
# ( while :; do echo 1 > foo/events/sched/sched_switch 2> /dev/null; done ) &
Luckily this can only be done by root user, but it should be fixed regardless.
The problem is that a delete of the file can happen after the write to the event
is opened, but before the enabling happens.
The solution is to make sure the trace_array is available before succeeding in
opening for write, and incerment the ref counter while opened.
Now the instance can be deleted when the events are writing to the buffer,
but the deletion of the instance will disable all events before the instance
is actually deleted.
Reported-by: Alexander Lam <azl@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 2a6c24afab70dbcfee49f4c76e1511eec1a3298b upstream.
While analyzing the code, I discovered that there's a potential race between
deleting a trace instance and setting events. There are a few races that can
occur if events are being traced as the buffer is being deleted. Mostly the
problem comes with freeing the descriptor used by the trace event callback.
To prevent problems like this, the events are disabled before the buffer is
deleted. The problem with the current solution is that the event_mutex is let
go between disabling the events and freeing the files, which means that the events
could be enabled again while the freeing takes place.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 7b85af63034818e43aee6c1d7bf1c7c6796a9073 upstream.
When a trace file is opened that may access a trace array, it must
increment its ref count to prevent it from being deleted.
Reported-by: Alexander Lam <azl@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ff451961a8b2a17667a7bfa39c86fb9b351445db upstream.
Commit a695cb58162 "tracing: Prevent deleting instances when they are being read"
tried to fix a race between deleting a trace instance and reading contents
of a trace file. But it wasn't good enough. The following could crash the kernel:
# cd /sys/kernel/debug/tracing/instances
# ( while :; do mkdir foo; rmdir foo; done ) &
# ( while :; do cat foo/trace &> /dev/null; done ) &
Luckily this can only be done by root user, but it should be fixed regardless.
The problem is that a delete of the file can happen after the reader starts
to open the file but before it grabs the trace_types_mutex.
The solution is to validate the trace array before using it. If the trace
array does not exist in the list of trace arrays, then it returns -ENODEV.
There's a possibility that a trace_array could be deleted and a new one
created and the open would open its file instead. But that is very minor as
it will just return the data of the new trace array, it may confuse the user
but it will not crash the system. As this can only be done by root anyway,
the race will only occur if root is deleting what its trying to read at
the same time.
Reported-by: Alexander Lam <azl@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit a82274151af2b075163e3c42c828529dee311487 upstream.
There are multiple places where the ftrace_trace_arrays list is accessed in
trace_events.c without the trace_types_lock held.
Link: http://lkml.kernel.org/r/1372732674-22726-1-git-send-email-azl@google.com
Signed-off-by: Alexander Z Lam <azl@google.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 2d71619c59fac95a5415a326162fa046161b938c upstream.
The trace_marker file was present for each new instance created, but it
added the trace mark to the global trace buffer instead of to
the instance's buffer.
Link: http://lkml.kernel.org/r/1372717885-4543-2-git-send-email-azl@google.com
Signed-off-by: Alexander Z Lam <azl@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 11034ae9c20f4057a6127fc965906417978e69b2 upstream.
All syscall tracing irqs-off tags are wrong, the syscall enter entry doesn't
disable irqs.
[root@jovi tracing]#echo "syscalls:sys_enter_open" > set_event
[root@jovi tracing]# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 13/13 #P:2
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
irqbalance-513 [000] d... 56115.496766: sys_open(filename: 804e1a6, flags: 0, mode: 1b6)
irqbalance-513 [000] d... 56115.497008: sys_open(filename: 804e1bb, flags: 0, mode: 1b6)
sendmail-771 [000] d... 56115.827982: sys_open(filename: b770e6d1, flags: 0, mode: 1b6)
The reason is syscall tracing doesn't record irq_flags into buffer.
The proper display is:
[root@jovi tracing]#echo "syscalls:sys_enter_open" > set_event
[root@jovi tracing]# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 14/14 #P:2
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
irqbalance-514 [001] .... 46.213921: sys_open(filename: 804e1a6, flags: 0, mode: 1b6)
irqbalance-514 [001] .... 46.214160: sys_open(filename: 804e1bb, flags: 0, mode: 1b6)
<...>-920 [001] .... 47.307260: sys_open(filename: 4e82a0c5, flags: 80000, mode: 0)
Link: http://lkml.kernel.org/r/1365564393-10972-3-git-send-email-jovi.zhangwei@huawei.com
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 6e94a780374ed31b280f939d4757e8d7858dff16 upstream.
Running the following:
# cd /sys/kernel/debug/tracing
# echo p:i do_sys_open > kprobe_events
# echo p:j schedule >> kprobe_events
# cat kprobe_events
p:kprobes/i do_sys_open
p:kprobes/j schedule
# echo p:i do_sys_open >> kprobe_events
# cat kprobe_events
p:kprobes/j schedule
p:kprobes/i do_sys_open
# ls /sys/kernel/debug/tracing/events/kprobes/
enable filter j
Notice that the 'i' is missing from the kprobes directory.
The console produces:
"Failed to create system directory kprobes"
This is because kprobes passes in a allocated name for the system
and the ftrace event subsystem saves off that name instead of creating
a duplicate for it. But the kprobes may free the system name making
the pointer to it invalid.
This bug was introduced by 92edca073c37 "tracing: Use direct field, type
and system names" which switched from using kstrdup() on the system name
in favor of just keeping apointer to it, as the internal ftrace event
system names are static and exist for the life of the computer being booted.
Instead of reverting back to duplicating system names again, we can use
core_kernel_data() to determine if the passed in name was allocated or
static. Then use the MSB of the ref_count to be a flag to keep track if
the name was allocated or not. Then we can still save from having to duplicate
strings that will always exist, but still copy the ones that may be freed.
Reported-by: "zhangwei(Jovi)" <jovi.zhangwei@huawei.com>
Reported-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit fa44063f9ef163c3a4c8d8c0465bb8a056b42035 upstream.
When wrong argument is passed into uprobe_events it does not return
an error:
[root@jovi tracing]# echo 'p:myprobe /bin/bash' > uprobe_events
[root@jovi tracing]#
The proper response is:
[root@jovi tracing]# echo 'p:myprobe /bin/bash' > uprobe_events
-bash: echo: write error: Invalid argument
Link: http://lkml.kernel.org/r/51B964FF.5000106@huawei.com
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: <srikar@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Outputting formats of x86-tsc and counter should be a raw format, but after
applying the patch(2b6080f28c7cc3efc8625ab71495aae89aeb63a0), the format was
changed to nanosec. This is because the global variable trace_clock_id was used.
When we use multiple buffers, clock_id of each sub-buffer should be used. Then,
this patch uses tr->clock_id instead of the global variable trace_clock_id.
[ Basically, this fixes a regression where the multibuffer code changed the
trace_clock file to update tr->clock_id but the traces still use the old
global trace_clock_id variable, negating the file's effect. The global
trace_clock_id variable is obsolete and removed. - SR ]
Link: http://lkml.kernel.org/r/20130423013239.22334.7394.stgit@yunodevel
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The irqsoff tracer records the max time that interrupts are disabled.
There are hooks in the assembly code that calls back into the tracer when
interrupts are disabled or enabled.
When they are enabled, the tracer checks if the amount of time they
were disabled is larger than the previous recorded max interrupts off
time. If it is, it creates a snapshot of the currently running trace
to store where the last largest interrupts off time was held and how
it happened.
During testing, this RCU lockdep dump appeared:
[ 1257.829021] ===============================
[ 1257.829021] [ INFO: suspicious RCU usage. ]
[ 1257.829021] 3.10.0-rc1-test+ #171 Tainted: G W
[ 1257.829021] -------------------------------
[ 1257.829021] /home/rostedt/work/git/linux-trace.git/include/linux/rcupdate.h:780 rcu_read_lock() used illegally while idle!
[ 1257.829021]
[ 1257.829021] other info that might help us debug this:
[ 1257.829021]
[ 1257.829021]
[ 1257.829021] RCU used illegally from idle CPU!
[ 1257.829021] rcu_scheduler_active = 1, debug_locks = 0
[ 1257.829021] RCU used illegally from extended quiescent state!
[ 1257.829021] 2 locks held by trace-cmd/4831:
[ 1257.829021] #0: (max_trace_lock){......}, at: [<ffffffff810e2b77>] stop_critical_timing+0x1a3/0x209
[ 1257.829021] #1: (rcu_read_lock){.+.+..}, at: [<ffffffff810dae5a>] __update_max_tr+0x88/0x1ee
[ 1257.829021]
[ 1257.829021] stack backtrace:
[ 1257.829021] CPU: 3 PID: 4831 Comm: trace-cmd Tainted: G W 3.10.0-rc1-test+ #171
[ 1257.829021] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
[ 1257.829021] 0000000000000001 ffff880065f49da8 ffffffff8153dd2b ffff880065f49dd8
[ 1257.829021] ffffffff81092a00 ffff88006bd78680 ffff88007add7500 0000000000000003
[ 1257.829021] ffff88006bd78680 ffff880065f49e18 ffffffff810daebf ffffffff810dae5a
[ 1257.829021] Call Trace:
[ 1257.829021] [<ffffffff8153dd2b>] dump_stack+0x19/0x1b
[ 1257.829021] [<ffffffff81092a00>] lockdep_rcu_suspicious+0x109/0x112
[ 1257.829021] [<ffffffff810daebf>] __update_max_tr+0xed/0x1ee
[ 1257.829021] [<ffffffff810dae5a>] ? __update_max_tr+0x88/0x1ee
[ 1257.829021] [<ffffffff811002b9>] ? user_enter+0xfd/0x107
[ 1257.829021] [<ffffffff810dbf85>] update_max_tr_single+0x11d/0x12d
[ 1257.829021] [<ffffffff811002b9>] ? user_enter+0xfd/0x107
[ 1257.829021] [<ffffffff810e2b15>] stop_critical_timing+0x141/0x209
[ 1257.829021] [<ffffffff8109569a>] ? trace_hardirqs_on+0xd/0xf
[ 1257.829021] [<ffffffff811002b9>] ? user_enter+0xfd/0x107
[ 1257.829021] [<ffffffff810e3057>] time_hardirqs_on+0x2a/0x2f
[ 1257.829021] [<ffffffff811002b9>] ? user_enter+0xfd/0x107
[ 1257.829021] [<ffffffff8109550c>] trace_hardirqs_on_caller+0x16/0x197
[ 1257.829021] [<ffffffff8109569a>] trace_hardirqs_on+0xd/0xf
[ 1257.829021] [<ffffffff811002b9>] user_enter+0xfd/0x107
[ 1257.829021] [<ffffffff810029b4>] do_notify_resume+0x92/0x97
[ 1257.829021] [<ffffffff8154bdca>] int_signal+0x12/0x17
What happened was entering into the user code, the interrupts were enabled
and a max interrupts off was recorded. The trace buffer was saved along with
various information about the task: comm, pid, uid, priority, etc.
The uid is recorded with task_uid(tsk). But this is a macro that uses rcu_read_lock()
to retrieve the data, and this happened to happen where RCU is blind (user_enter).
As only the preempt and irqs off tracers can have this happen, and they both
only have the tsk == current, if tsk == current, use current_uid() instead of
task_uid(), as current_uid() does not use RCU as only current can change its uid.
This fixes the RCU suspicious splat.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The branch selftest calls trace_test_buffer(), but with the new code
it expects the first parameter to be a pointer to a struct trace_buffer.
All self tests were changed but the branch selftest was missed.
This caused either a crash or failed test when the branch selftest was
enabled.
Link: http://lkml.kernel.org/r/20130529141333.GA24064@localhost
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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