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Message-Id: <20210712060947.494102365@linuxfoundation.org>
Date: Mon, 12 Jul 2021 08:03:58 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Tong Zhang <ztong0001@...il.com>,
Hans Verkuil <hverkuil-cisco@...all.nl>,
Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.12 155/700] media: bt878: do not schedule tasklet when it is not setup
From: Tong Zhang <ztong0001@...il.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@...il.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.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++;
--
2.30.2
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