FAILED: patch "[PATCH] media: au0828: fix use-after-free in bulk_timeout timer on" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-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 <[email protected]>.

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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 521030837bee352515d5ea57cc6a29581db3506e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026110422-surrender-slip-c8ba@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From 521030837bee352515d5ea57cc6a29581db3506e Mon Sep 17 00:00:00 2001
From: Fan Wu <[email protected]>
Date: Mon, 10 Aug 2026 05:51:28 +0000
Subject: [PATCH] media: au0828: fix use-after-free in bulk_timeout timer on
disconnect

start_urb_transfer() arms dev->bulk_timeout, whose callback au0828_bulk_timeout() queues dev->restart_streaming; that work in turn calls start_urb_transfer() and re-arms the timer.

au0828_dvb_unregister() cancels restart_streaming on disconnect but does not sync bulk_timeout. au0828_usb_release() then frees dev with kfree(), so a timer still armed or pending at that point can fire after the free and dereference dev through timer_container_of().

Sync the timer with timer_shutdown_sync() before cancel_work_sync(). The timer callback queues the work, so the timer must be stopped first; the shutdown variant is needed because the work re-arms the timer through start_urb_transfer(). The dvb->frontend == NULL early return guards the register-failure path where the timer was never set up.

This bug was found by static analysis.

index 9c95b7ceaecd..d3fff47f0edf 100644
@@ -537,6 +537,7 @@ void au0828_dvb_unregister(struct au0828_dev *dev)
 	if (dvb->frontend == NULL)
 		return;
 
+	timer_shutdown_sync(&dev->bulk_timeout);
 	cancel_work_sync(&dev->restart_streaming);
 
 	dvb_net_release(&dvb->net);