linux-kernel - [PATCH] wifi: cfg80211: Fix use-after-free in cfg80211_shutdown_all

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Message-ID: <20251223170452.75358-1-d.dulov@aladdin.ru>
Date: Tue, 23 Dec 2025 20:04:52 +0300
From: Daniil Dulov <d.dulov@...ddin.ru>
To: Johannes Berg <johannes@...solutions.net>
CC: Daniil Dulov <d.dulov@...ddin.ru>, "John W. Linville"
	<linville@...driver.com>, <linux-wireless@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <lvc-project@...uxtesting.org>,
	<stable@...r.kernel.org>
Subject: [PATCH] wifi: cfg80211: Fix use-after-free in cfg80211_shutdown_all_interfaces

There is a use-after-free error in cfg80211_shutdown_all_interfaces found
by syzkaller:

BUG: KASAN: use-after-free in cfg80211_shutdown_all_interfaces+0x213/0x220
Read of size 8 at addr ffff888112a78d98 by task kworker/0:5/5326
CPU: 0 UID: 0 PID: 5326 Comm: kworker/0:5 Not tainted 6.19.0-rc2 #2 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Workqueue: events cfg80211_rfkill_block_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x116/0x1f0
 print_report+0xcd/0x630
 kasan_report+0xe0/0x110
 cfg80211_shutdown_all_interfaces+0x213/0x220
 cfg80211_rfkill_block_work+0x1e/0x30
 process_one_work+0x9cf/0x1b70
 worker_thread+0x6c8/0xf10
 kthread+0x3c5/0x780
 ret_from_fork+0x56d/0x700
 ret_from_fork_asm+0x1a/0x30
 </TASK>

The problem arises due to the rfkill_block work is not cancelled when
cfg80211 device is being freed. In order to fix the issue cancel the
corresponding work before destroying rfkill in cfg80211_dev_free().

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 1f87f7d3a3b4 ("cfg80211: add rfkill support")
Cc: stable@...r.kernel.org
Signed-off-by: Daniil Dulov <d.dulov@...ddin.ru>
---
 net/wireless/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 54a34d8d356e..e94f69205f50 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1226,6 +1226,7 @@ void cfg80211_dev_free(struct cfg80211_registered_device *rdev)
 	spin_unlock_irqrestore(&rdev->wiphy_work_lock, flags);
 	cancel_work_sync(&rdev->wiphy_work);
 
+	cancel_work_sync(&rdev->rfkill_block);
 	rfkill_destroy(rdev->wiphy.rfkill);
 	list_for_each_entry_safe(reg, treg, &rdev->beacon_registrations, list) {
 		list_del(&reg->list);
-- 
2.34.1