diff options
| author | Matthew Dempsky <mdempsky@chromium.org> | 2014-06-06 14:36:42 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2014-07-11 13:33:47 +0100 |
| commit | 0b8ad905025a3b00172bcd245072a3ba98db0a52 (patch) | |
| tree | 953918ca2092ed2f3d034e56f4f3c52d902f20bc /kernel | |
| parent | 6df2529a3af404bc367fcf37cd3203c1d4951675 (diff) | |
ptrace: fix fork event messages across pid namespaces
commit 4e52365f279564cef0ddd41db5237f0471381093 upstream.
When tracing a process in another pid namespace, it's important for fork
event messages to contain the child's pid as seen from the tracer's pid
namespace, not the parent's. Otherwise, the tracer won't be able to
correlate the fork event with later SIGTRAP signals it receives from the
child.
We still risk a race condition if a ptracer from a different pid
namespace attaches after we compute the pid_t value. However, sending a
bogus fork event message in this unlikely scenario is still a vast
improvement over the status quo where we always send bogus fork event
messages to debuggers in a different pid namespace than the forking
process.
Signed-off-by: Matthew Dempsky <mdempsky@chromium.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Julien Tinnes <jln@chromium.org>
Cc: Roland McGrath <mcgrathr@chromium.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/fork.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index ce0c182f9a6..f51e55fb3a7 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1513,10 +1513,12 @@ long do_fork(unsigned long clone_flags, */ if (!IS_ERR(p)) { struct completion vfork; + struct pid *pid; trace_sched_process_fork(current, p); - nr = task_pid_vnr(p); + pid = get_task_pid(p, PIDTYPE_PID); + nr = pid_vnr(pid); if (clone_flags & CLONE_PARENT_SETTID) put_user(nr, parent_tidptr); @@ -1540,14 +1542,16 @@ long do_fork(unsigned long clone_flags, /* forking complete and child started to run, tell ptracer */ if (unlikely(trace)) - ptrace_event(trace, nr); + ptrace_event_pid(trace, pid); if (clone_flags & CLONE_VFORK) { freezer_do_not_count(); wait_for_completion(&vfork); freezer_count(); - ptrace_event(PTRACE_EVENT_VFORK_DONE, nr); + ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid); } + + put_pid(pid); } else { nr = PTR_ERR(p); } |