Uprobes: Fix kernel oops with delayed_uprobe_remove()

There could be a race between task exit and probe unregister:

  exit_mm()
  mmput()
  __mmput()                     uprobe_unregister()
  uprobe_clear_state()          put_uprobe()
  delayed_uprobe_remove()       delayed_uprobe_remove()

put_uprobe() is calling delayed_uprobe_remove() without taking
delayed_uprobe_lock and thus the race sometimes results in a
kernel crash. Fix this by taking delayed_uprobe_lock before
calling delayed_uprobe_remove() from put_uprobe().

Detailed crash log can be found at:
  Link: http://lkml.kernel.org/r/[email protected]

Link: http://lkml.kernel.org/r/[email protected]

Acked-by: Oleg Nesterov <[email protected]>
Reviewed-by: Srikar Dronamraju <[email protected]>
Reported-by: [email protected]
Fixes: 1cc33161a83d ("uprobes: Support SDT markers having reference count (semaphore)")
Signed-off-by: Ravi Bangoria <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

0 files changed, 0 insertions, 0 deletions