On Mon Jan 13 13:51:30 2025 +0300, Murad Masimov wrote:
> Syzkaller has reported a general protection fault at function
> ir_raw_event_store_with_filter(). This crash is caused by a NULL pointer
> dereference of dev->raw pointer, even though it is checked for NULL in
> the same function, which means there is a race condition. It occurs due
> to the incorrect order of actions in the streamzap_disconnect() function:
> rc_unregister_device() is called before usb_kill_urb(). The dev->raw
> pointer is freed and set to NULL in rc_unregister_device(), and only
> after that usb_kill_urb() waits for in-progress requests to finish.
>
> If rc_unregister_device() is called while streamzap_callback() handler is
> not finished, this can lead to accessing freed resources. Thus
> rc_unregister_device() should be called after usb_kill_urb().
>
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
>
> Fixes: 8e9e60640067 ("V4L/DVB: staging/lirc: port lirc_streamzap to ir-core")
> Cc: sta...@vger.kernel.org
> Reported-by: syzbot+34008406ee9a31b13...@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=34008406ee9a31b13c73
> Signed-off-by: Murad Masimov <m.masi...@mt-integration.ru>
> Signed-off-by: Sean Young <s...@mess.org>
> Signed-off-by: Hans Verkuil <hverk...@xs4all.nl>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/rc/streamzap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/drivers/media/rc/streamzap.c b/drivers/media/rc/streamzap.c
index 9b209e687f25..2ce62fe5d60f 100644
--- a/drivers/media/rc/streamzap.c
+++ b/drivers/media/rc/streamzap.c
@@ -385,8 +385,8 @@ static void streamzap_disconnect(struct usb_interface
*interface)
if (!sz)
return;
- rc_unregister_device(sz->rdev);
usb_kill_urb(sz->urb_in);
+ rc_unregister_device(sz->rdev);
usb_free_urb(sz->urb_in);
usb_free_coherent(usbdev, sz->buf_in_len, sz->buf_in, sz->dma_in);
