From: Tong Zhang ztong0001@gmail.com
[ Upstream commit a3a54bf4bddaecda8b5767209cfc703f0be2841d ]
There is a problem with the tasklet in bt878. bt->tasklet is set by dvb-bt8xx.ko, and bt878.ko can be loaded independently. In this case if interrupt comes it may cause null-ptr-dereference. To solve this issue, we check if the tasklet is actually set before calling tasklet_schedule.
[ 1.750438] bt878(0): irq FDSR FBUS risc_pc= [ 1.750728] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 1.752969] RIP: 0010:0x0 [ 1.757526] Call Trace: [ 1.757659] <IRQ> [ 1.757770] tasklet_action_common.isra.0+0x107/0x110 [ 1.758041] tasklet_action+0x22/0x30 [ 1.758237] __do_softirq+0xe0/0x29b [ 1.758430] irq_exit_rcu+0xa4/0xb0 [ 1.758618] common_interrupt+0x8d/0xa0 [ 1.758824] </IRQ>
Signed-off-by: Tong Zhang ztong0001@gmail.com Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/media/pci/bt8xx/bt878.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/media/pci/bt8xx/bt878.c b/drivers/media/pci/bt8xx/bt878.c index 78dd35c9b65d..7ca309121fb5 100644 --- a/drivers/media/pci/bt8xx/bt878.c +++ b/drivers/media/pci/bt8xx/bt878.c @@ -300,7 +300,8 @@ static irqreturn_t bt878_irq(int irq, void *dev_id) } if (astat & BT878_ARISCI) { bt->finished_block = (stat & BT878_ARISCS) >> 28; - tasklet_schedule(&bt->tasklet); + if (bt->tasklet.callback) + tasklet_schedule(&bt->tasklet); break; } count++;