* [PATCH v2] media: bt878: do not schedule tasklet when it is not setup
[not found] <acd47ab6-49b3-f00d-857d-1f5f42129e05@wanadoo.fr>
@ 2021-04-28 22:12 ` Tong Zhang
0 siblings, 0 replies; only message in thread
From: Tong Zhang @ 2021-04-28 22:12 UTC (permalink / raw)
To: Mauro Carvalho Chehab, Mike Rapoport, Andrew Morton,
Christophe JAILLET, Tong Zhang, linux-media, linux-kernel
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>
---
v2: fix coding style and commit log
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++;
--
2.25.1
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