This is a note to let you know that I've just added the patch titled
media: pvrusb2: fix use after free on context disconnection
to the 5.4-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-pvrusb2-fix-use-after-free-on-context-disconne.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d7ef6adafe7135851c38a82ffa478ef518427083
Author: Ricardo B. Marliere <ricardo@xxxxxxxxxxxx>
Date: Fri Oct 13 01:09:12 2023 +0200
media: pvrusb2: fix use after free on context disconnection
[ Upstream commit ded85b0c0edd8f45fec88783d7555a5b982449c1 ]
Upon module load, a kthread is created targeting the
pvr2_context_thread_func function, which may call pvr2_context_destroy
and thus call kfree() on the context object. However, that might happen
before the usb hub_event handler is able to notify the driver. This
patch adds a sanity check before the invalid read reported by syzbot,
within the context disconnection call stack.
Reported-and-tested-by: syzbot+621409285c4156a009b3@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/all/000000000000a02a4205fff8eb92@xxxxxxxxxx/
Fixes: e5be15c63804 ("V4L/DVB (7711): pvrusb2: Fix race on module unload")
Signed-off-by: Ricardo B. Marliere <ricardo@xxxxxxxxxxxx>
Acked-by: Mike Isely <isely@xxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/media/usb/pvrusb2/pvrusb2-context.c b/drivers/media/usb/pvrusb2/pvrusb2-context.c
index 14170a5d72b3..1764674de98b 100644
--- a/drivers/media/usb/pvrusb2/pvrusb2-context.c
+++ b/drivers/media/usb/pvrusb2/pvrusb2-context.c
@@ -268,7 +268,8 @@ void pvr2_context_disconnect(struct pvr2_context *mp)
{
pvr2_hdw_disconnect(mp->hdw);
mp->disconnect_flag = !0;
- pvr2_context_notify(mp);
+ if (!pvr2_context_shutok())
+ pvr2_context_notify(mp);
}
