FAILED: patch "[PATCH] wifi: libertas_tf: fix use-after-free in lbtf_free_adapter()" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x aa6dcd5c8dd9ba1d7d0f60093bcda41c0d6d438d
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026072010-corncob-unease-948d@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From aa6dcd5c8dd9ba1d7d0f60093bcda41c0d6d438d Mon Sep 17 00:00:00 2001
From: Maoyi Xie <[email protected]>
Date: Mon, 22 Jun 2026 15:53:38 +0800
Subject: [PATCH] wifi: libertas_tf: fix use-after-free in lbtf_free_adapter()

lbtf_free_adapter() calls timer_delete(&priv->command_timer), which does not wait for a running command_timer_fn() callback. lbtf_free_adapter() runs on the teardown path right before ieee80211_free_hw() frees priv, both in lbtf_remove_card() and in the probe error path. command_timer is armed by mod_timer() in lbtf_cmd() whenever a firmware command is sent. command_timer_fn() dereferences priv. If a command times out as the device is removed, command_timer_fn() runs concurrently with teardown and dereferences priv after it has been freed.

This is the same use-after-free that commit 03cc8f90d053 ("wifi: libertas:
fix use-after-free in lbs_free_adapter()") fixed in the sibling libertas driver. The libertas_tf variant has the identical pattern and was left unchanged. Use timer_delete_sync() so any in-flight callback completes before priv is freed.

index fb20fe31cd36..42be6fa22f9c 100644
@@ -174,7 +174,7 @@ static void lbtf_free_adapter(struct lbtf_private *priv)
 {
 	lbtf_deb_enter(LBTF_DEB_MAIN);
 	lbtf_free_cmd_buffer(priv);
-	timer_delete(&priv->command_timer);
+	timer_delete_sync(&priv->command_timer);
 	lbtf_deb_leave(LBTF_DEB_MAIN);
 }
 

From: Maoyi Xie <[email protected]>

[ Upstream commit aa6dcd5c8dd9ba1d7d0f60093bcda41c0d6d438d ]

lbtf_free_adapter() calls timer_delete(&priv->command_timer), which does not wait for a running command_timer_fn() callback. lbtf_free_adapter() runs on the teardown path right before ieee80211_free_hw() frees priv, both in lbtf_remove_card() and in the probe error path. command_timer is armed by mod_timer() in lbtf_cmd() whenever a firmware command is sent. command_timer_fn() dereferences priv. If a command times out as the device is removed, command_timer_fn() runs concurrently with teardown and dereferences priv after it has been freed.

This is the same use-after-free that commit 03cc8f90d053 ("wifi: libertas:
fix use-after-free in lbs_free_adapter()") fixed in the sibling libertas driver. The libertas_tf variant has the identical pattern and was left unchanged. Use timer_delete_sync() so any in-flight callback completes before priv is freed.

---
 drivers/net/wireless/marvell/libertas_tf/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 71492211904b34..b726e7e0b26084 100644
@@ -174,7 +174,7 @@ static void lbtf_free_adapter(struct lbtf_private *priv)
 {
 	lbtf_deb_enter(LBTF_DEB_MAIN);
 	lbtf_free_cmd_buffer(priv);
-	del_timer(&priv->command_timer);
+	timer_delete_sync(&priv->command_timer);
 	lbtf_deb_leave(LBTF_DEB_MAIN);
 }
 

2.53.0