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proc: io_accounting: Use new infrastructure to fix deadlocks in execve

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[ Upstream commit 76518d3798855242817e8a8ed76b2d72f4415624 ]

This changes do_io_accounting to use the new exec_update_mutex
instead of cred_guard_mutex.

This fixes possible deadlocks when the trace is accessing
/proc/$pid/io for instance.

This should be safe, as the credentials are only used for reading.

Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Bernd Edlinger 2020-03-20 21:27:41 +01:00 committed by Greg Kroah-Hartman
parent 4301db49e5
commit ba7eb0e48e
1 changed files with 2 additions and 2 deletions
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4
fs/proc/base.c
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@ -2770,7 +2770,7 @@ static int do_io_accounting(struct task_struct *task, struct seq_file *m, int wh
unsigned long flags;
int result;
result = mutex_lock_killable(&task->signal->cred_guard_mutex);
result = mutex_lock_killable(&task->signal->exec_update_mutex);
if (result)
return result;
@ -2806,7 +2806,7 @@ static int do_io_accounting(struct task_struct *task, struct seq_file *m, int wh
result = 0;
out_unlock:
mutex_unlock(&task->signal->cred_guard_mutex);
mutex_unlock(&task->signal->exec_update_mutex);
return result;
}