FAILED: patch "[PATCH] comedi: comedi_test: Fix possible deletion of uninitialized" 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 1b98304c09a0192598d0767f1eb8c83d7e793091
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025072155-viper-viewer-98bd@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 1b98304c09a0192598d0767f1eb8c83d7e793091 Mon Sep 17 00:00:00 2001
From: Ian Abbott <[email protected]>
Date: Tue, 8 Jul 2025 14:06:27 +0100
Subject: [PATCH] comedi: comedi_test: Fix possible deletion of uninitialized
timers

In waveform_common_attach(), the two timers &devpriv->ai_timer and &devpriv->ao_timer are initialized after the allocation of the device private data by comedi_alloc_devpriv() and the subdevices by comedi_alloc_subdevices(). The function may return with an error between those function calls. In that case, waveform_detach() will be called by the Comedi core to clean up. The check that waveform_detach() uses to decide whether to delete the timers is incorrect. It only checks that the device private data was allocated, but that does not guarantee that the timers were initialized. It also needs to check that the subdevices were allocated. Fix it.

index 9747e6d1f6eb..7984950f0f99 100644
@@ -792,7 +792,7 @@ static void waveform_detach(struct comedi_device *dev)
 {
 	struct waveform_private *devpriv = dev->private;
 
-	if (devpriv) {
+	if (devpriv && dev->n_subdevices) {
 		timer_delete_sync(&devpriv->ai_timer);
 		timer_delete_sync(&devpriv->ao_timer);
 	}

From: Ian Abbott <[email protected]>

[ Upstream commit 1b98304c09a0192598d0767f1eb8c83d7e793091 ]

In waveform_common_attach(), the two timers &devpriv->ai_timer and &devpriv->ao_timer are initialized after the allocation of the device private data by comedi_alloc_devpriv() and the subdevices by comedi_alloc_subdevices(). The function may return with an error between those function calls. In that case, waveform_detach() will be called by the Comedi core to clean up. The check that waveform_detach() uses to decide whether to delete the timers is incorrect. It only checks that the device private data was allocated, but that does not guarantee that the timers were initialized. It also needs to check that the subdevices were allocated. Fix it.

---
 drivers/staging/comedi/drivers/comedi_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index bea9a3adf08c8..f5199474c0e93 100644
@@ -790,7 +790,7 @@ static void waveform_detach(struct comedi_device *dev)
 {
 	struct waveform_private *devpriv = dev->private;
 
-	if (devpriv) {
+	if (devpriv && dev->n_subdevices) {
 		del_timer_sync(&devpriv->ai_timer);
 		del_timer_sync(&devpriv->ao_timer);
 	}

2.39.5