From patchwork Mon Mar 28 13:00:14 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Duoming Zhou X-Patchwork-Id: 12793518 X-Patchwork-Delegate: kuba@kernel.org 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 477DFC433FE for ; Mon, 28 Mar 2022 13:00:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242757AbiC1NCT (ORCPT ); Mon, 28 Mar 2022 09:02:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242173AbiC1NCQ (ORCPT ); Mon, 28 Mar 2022 09:02:16 -0400 Received: from zju.edu.cn (mail.zju.edu.cn [61.164.42.155]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DD4E95C378; Mon, 28 Mar 2022 06:00:32 -0700 (PDT) Received: from ubuntu.localdomain (unknown [10.15.192.164]) by mail-app2 (Coremail) with SMTP id by_KCgAXbxVfsUFikrWiAA--.62903S3; Mon, 28 Mar 2022 21:00:20 +0800 (CST) From: Duoming Zhou To: linux-hams@vger.kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, pabeni@redhat.com, kuba@kernel.org, davem@davemloft.net, ralf@linux-mips.org, jreuter@yaina.de, dan.carpenter@oracle.com, Duoming Zhou Subject: [PATCH net 1/2 V2] ax25: fix UAF bug in ax25_send_control() Date: Mon, 28 Mar 2022 21:00:14 +0800 Message-Id: <3a6285cd55b196a16cdf19603b16951a18f8387b.1648472006.git.duoming@zju.edu.cn> X-Mailer: git-send-email 2.17.1 In-Reply-To: References: In-Reply-To: References: X-CM-TRANSID: by_KCgAXbxVfsUFikrWiAA--.62903S3 X-Coremail-Antispam: 1UD129KBjvJXoWxWFyDtw1fKr4DArWrWr1xZrb_yoW5Gw45pF WUtFWrCryDJFWDAFs7KrWxWF18CayjqayDGryIqF1SkwnxJ3s8Ary8tryjqFy5Gr95KF18 Wa4vka1UAF1kZa7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvl1xkIjI8I6I8E6xAIw20EY4v20xvaj40_Wr0E3s1l1IIY67AE w4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2 IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2 z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcV Aq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r10 6r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64 vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7M4IIrI8v6xkF7I0E8cxan2IY04v7MxAIw28I cxkI7VAKI48JMxAIw28IcVCjz48v1sIEY20_GFWkJr1UJwCFx2IqxVCFs4IE7xkEbVWUJV W8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF 1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6x IIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvE x4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvj DU0xZFpf9x0JUZa9-UUUUU= X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAgcDAVZdtY7BCAAJs3 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org There are UAF bugs in ax25_send_control(), when we call ax25_release() to deallocate ax25_dev. The possible race condition is shown below: (Thread 1) | (Thread 2) ax25_dev_device_up() //(1) | | ax25_kill_by_device() ax25_bind() //(2) | ax25_connect() | ... ax25->state = AX25_STATE_1 | ... | ax25_dev_device_down() //(3) (Thread 3) ax25_release() | ax25_dev_put() //(4) FREE | case AX25_STATE_1: | ax25_send_control() | alloc_skb() //USE | The refcount of ax25_dev increases in position (1) and (2), and decreases in position (3) and (4). The ax25_dev will be freed before dereference sites in ax25_send_control(). The following is part of the report: [ 102.297448] BUG: KASAN: use-after-free in ax25_send_control+0x33/0x210 [ 102.297448] Read of size 8 at addr ffff888009e6e408 by task ax25_close/602 [ 102.297448] Call Trace: [ 102.303751] ax25_send_control+0x33/0x210 [ 102.303751] ax25_release+0x356/0x450 [ 102.305431] __sock_release+0x6d/0x120 [ 102.305431] sock_close+0xf/0x20 [ 102.305431] __fput+0x11f/0x420 [ 102.305431] task_work_run+0x86/0xd0 [ 102.307130] get_signal+0x1075/0x1220 [ 102.308253] arch_do_signal_or_restart+0x1df/0xc00 [ 102.308253] exit_to_user_mode_prepare+0x150/0x1e0 [ 102.308253] syscall_exit_to_user_mode+0x19/0x50 [ 102.308253] do_syscall_64+0x48/0x90 [ 102.308253] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 102.308253] RIP: 0033:0x405ae7 This patch defers the free operation of ax25_dev and net_device after all corresponding dereference sites in ax25_release() to avoid UAF. Fixes: 9fd75b66b8f6 ("ax25: Fix refcount leaks caused by ax25_cb_del()") Signed-off-by: Duoming Zhou --- Changes in V2: - Make commit message more clearer. net/ax25/af_ax25.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 992b6e5d85d..f5686c463bc 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -991,10 +991,6 @@ static int ax25_release(struct socket *sock) sock_orphan(sk); ax25 = sk_to_ax25(sk); ax25_dev = ax25->ax25_dev; - if (ax25_dev) { - dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker); - ax25_dev_put(ax25_dev); - } if (sk->sk_type == SOCK_SEQPACKET) { switch (ax25->state) { @@ -1056,6 +1052,10 @@ static int ax25_release(struct socket *sock) sk->sk_state_change(sk); ax25_destroy_socket(ax25); } + if (ax25_dev) { + dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker); + ax25_dev_put(ax25_dev); + } sock->sk = NULL; release_sock(sk);