From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 79C6B3B05BC; Mon, 17 Aug 2026 14:00:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975251; cv=none; b=OP1WbvWtGQjaNZJ3PfGaaYzU1iHTh+X7a8+sBnySmmnVT1rmGKsm2nHULkjklFhG4slr4YWlQt4MI9AKkrz8fqLJr9pxcfpBEE2oN/quBvZZ8UeCZC6IPZ3vEYGee4Tj+LoIHXLXCyStwO+knrnK0AN9bozZyYuuvNM7WreW+rc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975251; c=relaxed/simple; bh=5sK/OtYWNB4nvbM0mFDsfbyy6ierSoLcjHkykSvg05o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EzSJojtZrAXTOnelINvkjim5xUT8xqBBOTorZQulT58OvPztrNYHlyV1sF8RRJDLaN0JCWtayVWkvHP8rlrVEd2tYlhbo0ekvHIv8j7gFFV3Yu8jzlPvWKUnqGVAltzfdI6WfEhbK4aagxRZ5A5FGFXFCYx/NZgR24wSC1o8AIQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0ueHAWcS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0ueHAWcS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0DE21F00A3A; Mon, 17 Aug 2026 14:00:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786975250; bh=7XSAZYah2F4nBcT3bK0YROZQ5VOZ2A8Mq7ovQOemJGg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=0ueHAWcS+d65tbiuwoPd9EPiaYrP9juGtYsHYmypdoHey4yYbgmMDK4PVWLOVYcnW fAV1IS35OP2Y5BCPYTFYGpNQ3uCeCsLC2ZTimKOe4xmdySkQCd25VLkI8GLlTG7PEz KCMuCTF2zkrUNkKhXHx+danF4Cvnkna172sxUsvs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Baul Lee , Ido Schimmel , Paolo Abeni Subject: [PATCH 6.18 215/250] vxlan: do not arm the ageing timer on a device that is down Date: Mon, 17 Aug 2026 15:32:56 +0200 Message-ID: <20260817132545.323871010@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132536.466235697@linuxfoundation.org> References: <20260817132536.466235697@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Baul Lee commit b37971686ec59fb027fa4910ba16805e68fddb97 upstream. vxlan_changelink() arms vxlan->age_timer whenever the requested ageing interval differs from the configured one: if (conf.age_interval != vxlan->cfg.age_interval) mod_timer(&vxlan->age_timer, jiffies); There is no netif_running() test, so the timer is armed even on a device that was never brought up. The only synchronous cancel in the driver is the timer_delete_sync() in vxlan_stop(), which is .ndo_stop. netif_close_many() drops devices without IFF_UP before __dev_close_many() runs, so that cancel is skipped for such a device. vxlan_setup() sets dev->needs_free_netdev = true and age_timer is a member of struct vxlan_dev, so free_netdev() releases the allocation the timer lives in while it is still queued on a timer_base. expire_timers() unlinks the entry before it loads timer->function, so the timer core writes through the freed object's list pointers: BUG: KASAN: slab-use-after-free in __run_timers+0x208/0x654 Write of size 8 at addr ffff00001adace68 by task true/192 __asan_store8+0x84/0xac __run_timers+0x208/0x654 run_timer_softirq+0x154/0x18c Allocated by task 189: alloc_netdev_mqs+0x64/0x720 rtnl_create_link+0x4ac/0x520 rtnl_newlink+0x758/0xd00 Freed by task 191: netdev_release+0x40/0x58 netdev_run_todo+0x4a4/0x8c0 rtnl_dellink+0x200/0x4e8 The rtnl operations involved are netns-scoped, so an unprivileged user can perform them in a new user and network namespace. Arming the timer on a down device never had an effect: vxlan_cleanup() returns early on !netif_running(), and vxlan_open() arms the timer for any non-zero interval once the device is brought up. Add the missing test. Discovered by XBOW, triaged by Baul Lee Fixes: 40051c4dcad5 ("vxlan: Allow changing ageing time") Cc: stable@vger.kernel.org Signed-off-by: Baul Lee Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260809111829.78834-1-baul.lee@xbow.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman --- drivers/net/vxlan/vxlan_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/net/vxlan/vxlan_core.c +++ b/drivers/net/vxlan/vxlan_core.c @@ -4494,7 +4494,7 @@ static int vxlan_changelink(struct net_d if (change_igmp && vxlan_addr_multicast(&dst->remote_ip)) err = vxlan_multicast_leave(vxlan); - if (conf.age_interval != vxlan->cfg.age_interval) + if (netif_running(dev) && conf.age_interval != vxlan->cfg.age_interval) mod_timer(&vxlan->age_timer, jiffies); netdev_adjacent_change_commit(dst->remote_dev, lowerdev, dev);