From patchwork Tue Jun 23 12:28:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lihong Kou X-Patchwork-Id: 11620441 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A70FC618 for ; Tue, 23 Jun 2020 11:38:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9976320724 for ; Tue, 23 Jun 2020 11:38:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732427AbgFWLiA (ORCPT ); Tue, 23 Jun 2020 07:38:00 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:6822 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732332AbgFWLh7 (ORCPT ); Tue, 23 Jun 2020 07:37:59 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id EEEF89BA8FADCE3DF2EA; Tue, 23 Jun 2020 19:37:56 +0800 (CST) Received: from huawei.com (10.175.101.6) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.487.0; Tue, 23 Jun 2020 19:37:46 +0800 From: Lihong Kou To: , CC: , Subject: [PATCH] net: add a mutex lock to avoid UAF in do_enale_set Date: Tue, 23 Jun 2020 20:28:41 +0800 Message-ID: <20200623122841.9832-1-koulihong@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-CFilter-Loop: Reflected Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org In the case we set or free the global value listen_chan in different threads, we can encounter the UAF problems because the method is not protected by any lock, add one to avoid this bug. BUG: KASAN: use-after-free in l2cap_chan_close+0x48/0x990 net/bluetooth/l2cap_core.c:730 Read of size 8 at addr ffff888096950000 by task kworker/1:102/2868 CPU: 1 PID: 2868 Comm: kworker/1:102 Not tainted 5.5.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events do_enable_set Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fb/0x318 lib/dump_stack.c:118 print_address_description+0x74/0x5c0 mm/kasan/report.c:374 __kasan_report+0x149/0x1c0 mm/kasan/report.c:506 kasan_report+0x26/0x50 mm/kasan/common.c:641 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 l2cap_chan_close+0x48/0x990 net/bluetooth/l2cap_core.c:730 do_enable_set+0x660/0x900 net/bluetooth/6lowpan.c:1074 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Allocated by task 2870: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:515 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 kmem_cache_alloc_trace+0x221/0x2f0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] l2cap_chan_create+0x50/0x320 net/bluetooth/l2cap_core.c:446 chan_create net/bluetooth/6lowpan.c:640 [inline] bt_6lowpan_listen net/bluetooth/6lowpan.c:959 [inline] do_enable_set+0x6a4/0x900 net/bluetooth/6lowpan.c:1078 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Freed by task 2870: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10d/0x220 mm/slab.c:3757 l2cap_chan_destroy net/bluetooth/l2cap_core.c:484 [inline] kref_put include/linux/kref.h:65 [inline] l2cap_chan_put+0x170/0x190 net/bluetooth/l2cap_core.c:498 do_enable_set+0x66c/0x900 net/bluetooth/6lowpan.c:1075 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 The buggy address belongs to the object at ffff888096950000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 0 bytes inside of 2048-byte region [ffff888096950000, ffff888096950800) The buggy address belongs to the page: page:ffffea00025a5400 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea00027d1548 ffffea0002397808 ffff8880aa400e00 raw: 0000000000000000 ffff888096950000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809694ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88809694ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888096950000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888096950080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888096950100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Reported-by: syzbot+96414aa0033c363d8458@syzkaller.appspotmail.com Signed-off-by: Lihong Kou --- net/bluetooth/6lowpan.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c index bb55d92691b0..cff4944d5b66 100644 --- a/net/bluetooth/6lowpan.c +++ b/net/bluetooth/6lowpan.c @@ -50,6 +50,7 @@ static bool enable_6lowpan; /* We are listening incoming connections via this channel */ static struct l2cap_chan *listen_chan; +static DEFINE_MUTEX(set_lock); struct lowpan_peer { struct list_head list; @@ -1078,12 +1079,14 @@ static void do_enable_set(struct work_struct *work) enable_6lowpan = set_enable->flag; + mutex_lock(&set_lock); if (listen_chan) { l2cap_chan_close(listen_chan, 0); l2cap_chan_put(listen_chan); } listen_chan = bt_6lowpan_listen(); + mutex_unlock(&set_lock); kfree(set_enable); } @@ -1135,11 +1138,13 @@ static ssize_t lowpan_control_write(struct file *fp, if (ret == -EINVAL) return ret; + mutex_lock(&set_lock); if (listen_chan) { l2cap_chan_close(listen_chan, 0); l2cap_chan_put(listen_chan); listen_chan = NULL; } + mutex_unlock(&set_lock); if (conn) { struct lowpan_peer *peer;