FAILED: patch "[PATCH] media: streamzap: fix race between device disconnection and" failed to apply to 5.4-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x f656cfbc7a293a039d6a0c7100e1c846845148c1
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025040826-roving-harmony-dcd6@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f656cfbc7a293a039d6a0c7100e1c846845148c1 Mon Sep 17 00:00:00 2001
From: Murad Masimov <m.masimov@mt-integration.ru>
Date: Mon, 13 Jan 2025 13:51:30 +0300
Subject: [PATCH] media: streamzap: fix race between device disconnection and
 urb callback

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: stable@vger.kernel.org
Reported-by: syzbot+34008406ee9a31b13c73@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=34008406ee9a31b13c73
Signed-off-by: Murad Masimov <m.masimov@mt-integration.ru>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

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);