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Subject[PATCH 0/4] audit: refactor and fix for potential deadlock
Date
Commit 7ffb8e317bae ("audit: we don't need to
__set_current_state(TASK_RUNNING)") accidentally moved queue full check
before add_wait_queue_exclusive() which introduced the following race:

CPU1 CPU2
======== ========
(in audit_log_start()) (in kauditd_thread())

queue is full
wake_up(&audit_backlog_wait)
wait_event_freezable()
add_wait_queue_exclusive()
...
schedule_timeout()

Once this happens, both audit_log_start() and kauditd_thread() can cause
deadlock for up to backlog_wait_time waiting for each other. To prevent
the race, this patch adds queue full check after
prepare_to_wait_exclusive().

This patchset consists of the following parts:

Patch 1-3: Refactorings and a small fix preferable for deadlock fix
Patch 4: Actual deadlock fix

Eiichi Tsukata (4):
audit: refactor queue full checks
audit: account backlog waiting time in audit_receive()
audit: convert DECLARE_WAITQUEUE to DEFINE_WAIT
audit: check if queue is full after prepare_to_wait_exclusive()

kernel/audit.c | 71 ++++++++++++++++++++++++++++++--------------------
1 file changed, 43 insertions(+), 28 deletions(-)

--
2.40.0

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