From: Ricardo B. Marliere Date: Thu, 12 Oct 2023 23:09:12 +0000 (+0200) Subject: media: pvrusb2: fix use after free on context disconnection X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ded85b0c0edd8f45fec88783d7555a5b982449c1;p=linux.git media: pvrusb2: fix use after free on context disconnection 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 Acked-by: Mike Isely Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- diff --git a/drivers/media/usb/pvrusb2/pvrusb2-context.c b/drivers/media/usb/pvrusb2/pvrusb2-context.c index 14170a5d72b35..1764674de98bc 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); }