From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A69F5C433F5 for ; Tue, 9 Nov 2021 01:18:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8513961215 for ; Tue, 9 Nov 2021 01:18:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239969AbhKIBVV (ORCPT ); Mon, 8 Nov 2021 20:21:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:44358 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242264AbhKIBRL (ORCPT ); Mon, 8 Nov 2021 20:17:11 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1B2C961AED; Tue, 9 Nov 2021 01:06:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1636420014; bh=I2o6nHxO20gFl7KxzgRuNj8rn4mK5kS0r16cu7C+wx4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EjZHi2vpcYop/47jZnP29HwXU2voU/IveVVksVReGDriAQsnnLbwjexvZ0MEIwPEg D9qpRv28pGwSz4a2kW0+rbdxX81irdjLjtOoB0yH/tn78sNh6vttHXrKcUw2yXqWEb PFXZi7h5AIqzz1J8GCf4S8HHNomxzwvPHLybvBBFauh3KKRVHljQkIenzU9y7bBSCM Q4eoRmL0BeKcWuPQIyrK/EJIvB7QifGZqmxKqukZPVOkp6380gGDF178qzSdJ3bSR5 gh+ZTqYLx3phUC8WuKQL1h0KoHE1n83UjUeo6/eQ2oQfATlhzlpy9o+354pdCuj2Rx I+yrW3NHk80rw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Wang ShaoBo , Luiz Augusto von Dentz , Marcel Holtmann , Sasha Levin , johan.hedberg@gmail.com, luiz.dentz@gmail.com, davem@davemloft.net, kuba@kernel.org, linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 02/39] Bluetooth: fix use-after-free error in lock_sock_nested() Date: Mon, 8 Nov 2021 20:06:12 -0500 Message-Id: <20211109010649.1191041-2-sashal@kernel.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211109010649.1191041-1-sashal@kernel.org> References: <20211109010649.1191041-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wang ShaoBo [ Upstream commit 1bff51ea59a9afb67d2dd78518ab0582a54a472c ] use-after-free error in lock_sock_nested is reported: [ 179.140137][ T3731] ===================================================== [ 179.142675][ T3731] BUG: KMSAN: use-after-free in lock_sock_nested+0x280/0x2c0 [ 179.145494][ T3731] CPU: 4 PID: 3731 Comm: kworker/4:2 Not tainted 5.12.0-rc6+ #54 [ 179.148432][ T3731] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 [ 179.151806][ T3731] Workqueue: events l2cap_chan_timeout [ 179.152730][ T3731] Call Trace: [ 179.153301][ T3731] dump_stack+0x24c/0x2e0 [ 179.154063][ T3731] kmsan_report+0xfb/0x1e0 [ 179.154855][ T3731] __msan_warning+0x5c/0xa0 [ 179.155579][ T3731] lock_sock_nested+0x280/0x2c0 [ 179.156436][ T3731] ? kmsan_get_metadata+0x116/0x180 [ 179.157257][ T3731] l2cap_sock_teardown_cb+0xb8/0x890 [ 179.158154][ T3731] ? __msan_metadata_ptr_for_load_8+0x10/0x20 [ 179.159141][ T3731] ? kmsan_get_metadata+0x116/0x180 [ 179.159994][ T3731] ? kmsan_get_shadow_origin_ptr+0x84/0xb0 [ 179.160959][ T3731] ? l2cap_sock_recv_cb+0x420/0x420 [ 179.161834][ T3731] l2cap_chan_del+0x3e1/0x1d50 [ 179.162608][ T3731] ? kmsan_get_metadata+0x116/0x180 [ 179.163435][ T3731] ? kmsan_get_shadow_origin_ptr+0x84/0xb0 [ 179.164406][ T3731] l2cap_chan_close+0xeea/0x1050 [ 179.165189][ T3731] ? kmsan_internal_unpoison_shadow+0x42/0x70 [ 179.166180][ T3731] l2cap_chan_timeout+0x1da/0x590 [ 179.167066][ T3731] ? __msan_metadata_ptr_for_load_8+0x10/0x20 [ 179.168023][ T3731] ? l2cap_chan_create+0x560/0x560 [ 179.168818][ T3731] process_one_work+0x121d/0x1ff0 [ 179.169598][ T3731] worker_thread+0x121b/0x2370 [ 179.170346][ T3731] kthread+0x4ef/0x610 [ 179.171010][ T3731] ? process_one_work+0x1ff0/0x1ff0 [ 179.171828][ T3731] ? kthread_blkcg+0x110/0x110 [ 179.172587][ T3731] ret_from_fork+0x1f/0x30 [ 179.173348][ T3731] [ 179.173752][ T3731] Uninit was created at: [ 179.174409][ T3731] kmsan_internal_poison_shadow+0x5c/0xf0 [ 179.175373][ T3731] kmsan_slab_free+0x76/0xc0 [ 179.176060][ T3731] kfree+0x3a5/0x1180 [ 179.176664][ T3731] __sk_destruct+0x8af/0xb80 [ 179.177375][ T3731] __sk_free+0x812/0x8c0 [ 179.178032][ T3731] sk_free+0x97/0x130 [ 179.178686][ T3731] l2cap_sock_release+0x3d5/0x4d0 [ 179.179457][ T3731] sock_close+0x150/0x450 [ 179.180117][ T3731] __fput+0x6bd/0xf00 [ 179.180787][ T3731] ____fput+0x37/0x40 [ 179.181481][ T3731] task_work_run+0x140/0x280 [ 179.182219][ T3731] do_exit+0xe51/0x3e60 [ 179.182930][ T3731] do_group_exit+0x20e/0x450 [ 179.183656][ T3731] get_signal+0x2dfb/0x38f0 [ 179.184344][ T3731] arch_do_signal_or_restart+0xaa/0xe10 [ 179.185266][ T3731] exit_to_user_mode_prepare+0x2d2/0x560 [ 179.186136][ T3731] syscall_exit_to_user_mode+0x35/0x60 [ 179.186984][ T3731] do_syscall_64+0xc5/0x140 [ 179.187681][ T3731] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 179.188604][ T3731] ===================================================== In our case, there are two Thread A and B: Context: Thread A: Context: Thread B: l2cap_chan_timeout() __se_sys_shutdown() l2cap_chan_close() l2cap_sock_shutdown() l2cap_chan_del() l2cap_chan_close() l2cap_sock_teardown_cb() l2cap_sock_teardown_cb() Once l2cap_sock_teardown_cb() excuted, this sock will be marked as SOCK_ZAPPED, and can be treated as killable in l2cap_sock_kill() if sock_orphan() has excuted, at this time we close sock through sock_close() which end to call l2cap_sock_kill() like Thread C: Context: Thread C: sock_close() l2cap_sock_release() sock_orphan() l2cap_sock_kill() #free sock if refcnt is 1 If C completed, Once A or B reaches l2cap_sock_teardown_cb() again, use-after-free happened. We should set chan->data to NULL if sock is destructed, for telling teardown operation is not allowed in l2cap_sock_teardown_cb(), and also we should avoid killing an already killed socket in l2cap_sock_close_cb(). Signed-off-by: Wang ShaoBo Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Marcel Holtmann Signed-off-by: Sasha Levin --- net/bluetooth/l2cap_sock.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index 3905af1d300f7..13d070e7738db 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -1329,6 +1329,9 @@ static void l2cap_sock_close_cb(struct l2cap_chan *chan) { struct sock *sk = chan->data; + if (!sk) + return; + l2cap_sock_kill(sk); } @@ -1337,6 +1340,9 @@ static void l2cap_sock_teardown_cb(struct l2cap_chan *chan, int err) struct sock *sk = chan->data; struct sock *parent; + if (!sk) + return; + BT_DBG("chan %p state %s", chan, state_to_string(chan->state)); /* This callback can be called both for server (BT_LISTEN) @@ -1520,8 +1526,10 @@ static void l2cap_sock_destruct(struct sock *sk) { BT_DBG("sk %p", sk); - if (l2cap_pi(sk)->chan) + if (l2cap_pi(sk)->chan) { + l2cap_pi(sk)->chan->data = NULL; l2cap_chan_put(l2cap_pi(sk)->chan); + } if (l2cap_pi(sk)->rx_busy_skb) { kfree_skb(l2cap_pi(sk)->rx_busy_skb); -- 2.33.0