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media: dvb-core: Fix kernel WARNING for blocking operation in wait_event*()

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Using a semaphore in the wait_event*() condition is no good idea.
It hits a kernel WARN_ON() at prepare_to_wait_event() like:
  do not call blocking ops when !TASK_RUNNING; state=1 set at
  prepare_to_wait_event+0x6d/0x690

For avoiding the potential deadlock, rewrite to an open-coded loop
instead.  Unlike the loop in wait_event*(), this uses wait_woken()
after the condition check, hence the task state stays consistent.

CVE-2023-31084 was assigned to this bug.

Link: https://lore.kernel.org/r/CA+UBctCu7fXn4q41O_3=id1+OdyQ85tZY1x+TkT-6OVBL6KAUw@mail.gmail.com/

Link: https://lore.kernel.org/linux-media/20230512151800.1874-1-tiwai@suse.de
Reported-by: Yu Hao <yhao016@ucr.edu>
Closes: https://nvd.nist.gov/vuln/detail/CVE-2023-31084
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
This commit is contained in:
Takashi Iwai 2023-05-12 16:18:00 +01:00 committed by Mauro Carvalho Chehab
parent 627bb528b0
commit b8c75e4a1b
1 changed files with 12 additions and 4 deletions
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16
drivers/media/dvb-core/dvb_frontend.c
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@ -293,14 +293,22 @@ static int dvb_frontend_get_event(struct dvb_frontend *fe,
}
if (events->eventw == events->eventr) {
int ret;
struct wait_queue_entry wait;
int ret = 0;
if (flags & O_NONBLOCK)
return -EWOULDBLOCK;
ret = wait_event_interruptible(events->wait_queue,
dvb_frontend_test_event(fepriv, events));
init_waitqueue_entry(&wait, current);
add_wait_queue(&events->wait_queue, &wait);
while (!dvb_frontend_test_event(fepriv, events)) {
wait_woken(&wait, TASK_INTERRUPTIBLE, 0);
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
}
remove_wait_queue(&events->wait_queue, &wait);
if (ret < 0)
return ret;
}