This is a note to let you know that I've just added the patch titled
media: dvb-core: Fix kernel WARNING for blocking operation in wait_event*()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-dvb-core-fix-kernel-warning-for-blocking-opera.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4f165ab8191d3344c21e000de5fce5dc21a3a32e
Author: Takashi Iwai <tiwai@xxxxxxx>
Date: Fri May 12 16:18:00 2023 +0100
media: dvb-core: Fix kernel WARNING for blocking operation in wait_event*()
[ Upstream commit b8c75e4a1b325ea0a9433fa8834be97b5836b946 ]
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@xxxxxxxxxxxxxx/
Link: https://lore.kernel.org/linux-media/20230512151800.1874-1-tiwai@xxxxxxx
Reported-by: Yu Hao <yhao016@xxxxxxx>
Closes: https://nvd.nist.gov/vuln/detail/CVE-2023-31084
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index e0650bc2df613..90acf52cc253c 100644
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -304,14 +304,22 @@ 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;
}
