linux/kernel, branch v3.13.8

printk: fix syslog() overflowing user buffer

2014-03-31T17:05:15Z

commit e4178d809fdaee32a56833fff1f5056c99e90a1a upstream. This is not a buffer overflow in the traditional sense: we don't overflow any *kernel* buffers, but we do mis-count the amount of data we copy back to user space for the SYSLOG_ACTION_READ_ALL case. In particular, if the user buffer is too small to hold everything, and *if* there is a continuation line at just the right place, we can end up giving the user more data than he asked for. The reason is that we first count up the number of bytes all the log records contains, then we walk the records again until we've skipped the records at the beginning that won't fit, and then we walk the rest of the records and copy them to the user space buffer. And in between that "skip the initial records that won't fit" and the "copy the records that *will* fit to user space", we reset the 'prev' variable that contained the record information for the last record not copied. That meant that when we started copying to user space, we now had a different character count than what we had originally calculated in the first record walk-through. The fix is to simply not clear the 'prev' flags value (in both cases where we had the same logic: syslog_print_all and kmsg_dump_get_buffer: the latter is used for pstore-like dumping) Reported-and-tested-by: Debabrata Banerjee Acked-by: Kay Sievers Cc: Jeff Mahoney Signed-off-by: Linus Torvalds Cc: Josh Hunt Signed-off-by: Greg Kroah-Hartman

stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus()

2014-03-31T17:05:14Z

commit 177c53d943368fc97644ebc0a250dc8e2d124250 upstream. We must use smp_call_function_single(.wait=1) for the irq_cpu_stop_queue_work() to ensure the queueing is actually done under stop_cpus_lock. Without this we could have dropped the lock by the time we do the queueing and get the race we tried to fix. Fixes: 7053ea1a34fa ("stop_machine: Fix race between stop_two_cpus() and stop_cpus()") Signed-off-by: Peter Zijlstra Cc: Prarit Bhargava Cc: Rik van Riel Cc: Mel Gorman Cc: Christoph Hellwig Cc: Andrew Morton Link: http://lkml.kernel.org/r/20140228123905.GK3104@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

tracing: Fix array size mismatch in format string

2014-03-31T17:05:14Z

commit 87291347c49dc40aa339f587b209618201c2e527 upstream. In event format strings, the array size is reported in two locations. One in array subscript and then via the "size:" attribute. The values reported there have a mismatch. For e.g., in sched:sched_switch the prev_comm and next_comm character arrays have subscript values as [32] where as the actual field size is 16. name: sched_switch ID: 301 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1;signed:0; field:int common_pid; offset:4; size:4; signed:1; field:char prev_comm[32]; offset:8; size:16; signed:1; field:pid_t prev_pid; offset:24; size:4; signed:1; field:int prev_prio; offset:28; size:4; signed:1; field:long prev_state; offset:32; size:8; signed:1; field:char next_comm[32]; offset:40; size:16; signed:1; field:pid_t next_pid; offset:56; size:4; signed:1; field:int next_prio; offset:60; size:4; signed:1; After bisection, the following commit was blamed: 92edca0 tracing: Use direct field, type and system names This commit removes the duplication of strings for field->name and field->type assuming that all the strings passed in __trace_define_field() are immutable. This is not true for arrays, where the type string is created in event_storage variable and field->type for all array fields points to event_storage. Use __stringify() to create a string constant for the type string. Also, get rid of event_storage and event_storage_mutex that are not needed anymore. also, an added benefit is that this reduces the overhead of events a bit more: text data bss dec hex filename 8424787 2036472 1302528 11763787 b3804b vmlinux 8420814 2036408 1302528 11759750 b37086 vmlinux.patched Link: http://lkml.kernel.org/r/1392349908-29685-1-git-send-email-vnagarnaik@google.com Cc: Laurent Chavey Signed-off-by: Vaibhav Nagarnaik Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

audit: don't generate loginuid log when audit disabled

2014-03-24T04:44:19Z

commit c2412d91c68426e22add16550f97ae5cd988a159 upstream. If audit is disabled, we shouldn't generate loginuid audit log. Acked-by: Eric Paris Signed-off-by: Gao feng Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris Signed-off-by: Greg Kroah-Hartman

tracing: Do not add event files for modules that fail tracepoints

2014-03-24T04:44:10Z

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 Cc: Rusty Russell Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

cpuset: fix a race condition in __cpuset_node_allowed_softwall()

2014-03-24T04:44:09Z

commit 99afb0fd5f05aac467ffa85c36778fec4396209b upstream. It's not safe to access task's cpuset after releasing task_lock(). Holding callback_mutex won't help. Signed-off-by: Li Zefan Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

cpuset: fix a locking issue in cpuset_migrate_mm()

2014-03-24T04:44:09Z

commit 4729583006772b9530404bc1bb7c3aa4a10ffd4d upstream. I can trigger a lockdep warning: # mount -t cgroup -o cpuset xxx /cgroup # mkdir /cgroup/cpuset # mkdir /cgroup/tmp # echo 0 > /cgroup/tmp/cpuset.cpus # echo 0 > /cgroup/tmp/cpuset.mems # echo 1 > /cgroup/tmp/cpuset.memory_migrate # echo $$ > /cgroup/tmp/tasks # echo 1 > /cgruop/tmp/cpuset.mems =============================== [ INFO: suspicious RCU usage. ] 3.14.0-rc1-0.1-default+ #32 Not tainted ------------------------------- include/linux/cgroup.h:682 suspicious rcu_dereference_check() usage! ... [] dump_stack+0x72/0x86 [] lockdep_rcu_suspicious+0x101/0x140 [] cpuset_migrate_mm+0xb1/0xe0 ... We used to hold cgroup_mutex when calling cpuset_migrate_mm(), but now we hold cpuset_mutex, which causes task_css() to complain. This is not a false-positive but a real issue. Holding cpuset_mutex won't prevent a task from migrating to another cpuset, and it won't prevent the original task->cgroup from destroying during this change. Fixes: 5d21cc2db040 (cpuset: replace cgroup_mutex locking with cpuset internal locking) Signed-off-by: Li Zefan Sigend-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

genirq: Remove racy waitqueue_active check

2014-03-24T04:44:09Z

commit c685689fd24d310343ac33942e9a54a974ae9c43 upstream. We hit one rare case below: T1 calling disable_irq(), but hanging at synchronize_irq() always; The corresponding irq thread is in sleeping state; And all CPUs are in idle state; After analysis, we found there is one possible scenerio which causes T1 is waiting there forever: CPU0 CPU1 synchronize_irq() wait_event() spin_lock() atomic_dec_and_test(&threads_active) insert the __wait into queue spin_unlock() if(waitqueue_active) atomic_read(&threads_active) wake_up() Here after inserted the __wait into queue on CPU0, and before test if queue is empty on CPU1, there is no barrier, it maybe cause it is not visible for CPU1 immediately, although CPU0 has updated the queue list. It is similar for CPU0 atomic_read() threads_active also. So we'd need one smp_mb() before waitqueue_active.that, but removing the waitqueue_active() check solves it as wel l and it makes things simple and clear. Signed-off-by: Chuansheng Liu Cc: Xiaoming Wang Link: http://lkml.kernel.org/r/1393212590-32543-1-git-send-email-chuansheng.liu@intel.com Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

sched: Fix double normalization of vruntime

2014-03-24T04:43:59Z

commit 791c9e0292671a3bfa95286bb5c08129d8605618 upstream. dequeue_entity() is called when p->on_rq and sets se->on_rq = 0 which appears to guarentee that the !se->on_rq condition is met. If the task has done set_current_state(TASK_INTERRUPTIBLE) without schedule() the second condition will be met and vruntime will be incorrectly adjusted twice. In certain cases this can result in the task's vruntime never increasing past the vruntime of other tasks on the CFS' run queue, starving them of CPU time. This patch changes switched_from_fair() to use !p->on_rq instead of !se->on_rq. I'm able to cause a task with a priority of 120 to starve all other tasks with the same priority on an ARM platform running 3.2.51-rt72 PREEMPT RT by writing one character at time to a serial tty (16550 UART) in a tight loop. I'm also able to verify making this change corrects the problem on that platform and kernel version. Signed-off-by: George McCollister Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1392767811-28916-1-git-send-email-george.mccollister@gmail.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

perf: Fix hotplug splat

2014-03-07T06:06:27Z

commit e3703f8cdfcf39c25c4338c3ad8e68891cca3731 upstream. Drew Richardson reported that he could make the kernel go *boom* when hotplugging while having perf events active. It turned out that when you have a group event, the code in __perf_event_exit_context() fails to remove the group siblings from the context. We then proceed with destroying and freeing the event, and when you re-plug the CPU and try and add another event to that CPU, things go *boom* because you've still got dead entries there. Reported-by: Drew Richardson Signed-off-by: Peter Zijlstra Cc: Will Deacon Link: http://lkml.kernel.org/n/tip-k6v5wundvusvcseqj1si0oz0@git.kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman