From: Takashi Iwai tiwai@suse.de
[ 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-6OVBL6KAU...
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/media/dvb-core/dvb_frontend.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index e3a4a4688c2ec..651234584eb2c 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -301,14 +301,22 @@ 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; }