From ded85b0c0edd8f45fec88783d7555a5b982449c1 Mon Sep 17 00:00:00 2001
From: "Ricardo B. Marliere" <ricardo@marliere.net>
Date: Fri, 13 Oct 2023 01:09:12 +0200
Subject: [PATCH] media: pvrusb2: fix use after free on context disconnection
Git-commit: ded85b0c0edd8f45fec88783d7555a5b982449c1
Patch-mainline: v6.8-rc1
References: CVE-2023-52445 bsc#1220241
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@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000a02a4205fff8eb92@google.com/
Fixes: e5be15c63804 ("V4L/DVB (7711): pvrusb2: Fix race on module unload")
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Acked-by: Mike Isely <isely@pobox.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/media/usb/pvrusb2/pvrusb2-context.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
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);
}
--
2.35.3