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 X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,NORMAL_HTTP_TO_IP,NUMERIC_HTTP_ADDR, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29672C76191 for ; Wed, 24 Jul 2019 09:12:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3188229F4 for ; Wed, 24 Jul 2019 09:12:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726816AbfGXJMI (ORCPT ); Wed, 24 Jul 2019 05:12:08 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:2713 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726070AbfGXJMF (ORCPT ); Wed, 24 Jul 2019 05:12:05 -0400 Received: from DGGEMS403-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 4DA9FB7A80CE06172639; Wed, 24 Jul 2019 17:12:02 +0800 (CST) Received: from localhost.localdomain.localdomain (10.175.113.25) by DGGEMS403-HUB.china.huawei.com (10.3.19.203) with Microsoft SMTP Server id 14.3.439.0; Wed, 24 Jul 2019 17:11:56 +0800 From: Mao Wenan To: , , , CC: Mao Wenan Subject: [PATCH 4.4 stable net] net: tcp: Fix use-after-free in tcp_write_xmit Date: Wed, 24 Jul 2019 17:17:15 +0800 Message-ID: <20190724091715.137033-1-maowenan@huawei.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.113.25] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org There is one report about tcp_write_xmit use-after-free with version 4.4.136: BUG: KASAN: use-after-free in tcp_skb_pcount include/net/tcp.h:796 [inline] BUG: KASAN: use-after-free in tcp_init_tso_segs net/ipv4/tcp_output.c:1619 [inline] BUG: KASAN: use-after-free in tcp_write_xmit+0x3fc2/0x4cb0 net/ipv4/tcp_output.c:2056 Read of size 2 at addr ffff8801d6fc87b0 by task syz-executor408/4195 CPU: 0 PID: 4195 Comm: syz-executor408 Not tainted 4.4.136-gfb7e319 #59 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 7d8f38ecc03be946 ffff8801d73b7710 ffffffff81e0edad ffffea00075bf200 ffff8801d6fc87b0 0000000000000000 ffff8801d6fc87b0 dffffc0000000000 ffff8801d73b7748 ffffffff815159b6 ffff8801d6fc87b0 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x124 lib/dump_stack.c:51 [] print_address_description+0x6c/0x216 mm/kasan/report.c:252 [] kasan_report_error mm/kasan/report.c:351 [inline] [] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408 [] __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:427 [] tcp_skb_pcount include/net/tcp.h:796 [inline] [] tcp_init_tso_segs net/ipv4/tcp_output.c:1619 [inline] [] tcp_write_xmit+0x3fc2/0x4cb0 net/ipv4/tcp_output.c:2056 [] __tcp_push_pending_frames+0xa0/0x290 net/ipv4/tcp_output.c:2307 [] tcp_send_fin+0x176/0xab0 net/ipv4/tcp_output.c:2883 [] tcp_close+0xca0/0xf70 net/ipv4/tcp.c:2112 [] inet_release+0xff/0x1d0 net/ipv4/af_inet.c:435 [] sock_release+0x96/0x1c0 net/socket.c:586 [] sock_close+0x16/0x20 net/socket.c:1037 [] __fput+0x235/0x6f0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x10f/0x190 kernel/task_work.c:115 [] exit_task_work include/linux/task_work.h:21 [inline] [] do_exit+0x9e5/0x26b0 kernel/exit.c:759 [] do_group_exit+0x111/0x330 kernel/exit.c:889 [] get_signal+0x4ec/0x14b0 kernel/signal.c:2321 [] do_signal+0x8b/0x1d30 arch/x86/kernel/signal.c:712 [] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:248 [] prepare_exit_to_usermode arch/x86/entry/common.c:283 [inline] [] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:348 [] int_ret_from_sys_call+0x25/0xa3 Allocated by task 4194: [] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [] save_stack+0x43/0xd0 mm/kasan/kasan.c:512 [] set_track mm/kasan/kasan.c:524 [inline] [] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616 [] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554 [] slab_post_alloc_hook mm/slub.c:1349 [inline] [] slab_alloc_node mm/slub.c:2615 [inline] [] slab_alloc mm/slub.c:2623 [inline] [] kmem_cache_alloc+0xbe/0x2a0 mm/slub.c:2628 [] kmem_cache_alloc_node include/linux/slab.h:350 [inline] [] __alloc_skb+0xe6/0x600 net/core/skbuff.c:218 [] alloc_skb_fclone include/linux/skbuff.h:856 [inline] [] sk_stream_alloc_skb+0xa3/0x5d0 net/ipv4/tcp.c:833 [] tcp_sendmsg+0xd34/0x2b00 net/ipv4/tcp.c:1178 [] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755 [] sock_sendmsg_nosec net/socket.c:625 [inline] [] sock_sendmsg+0xcc/0x110 net/socket.c:635 [] SYSC_sendto+0x21c/0x370 net/socket.c:1665 [] SyS_sendto+0x40/0x50 net/socket.c:1633 [] entry_SYSCALL_64_fastpath+0x22/0x9e Freed by task 4194: [] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63 [] save_stack+0x43/0xd0 mm/kasan/kasan.c:512 [] set_track mm/kasan/kasan.c:524 [inline] [] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:589 [] slab_free_hook mm/slub.c:1383 [inline] [] slab_free_freelist_hook mm/slub.c:1405 [inline] [] slab_free mm/slub.c:2859 [inline] [] kmem_cache_free+0xbe/0x340 mm/slub.c:2881 [] kfree_skbmem+0xcf/0x100 net/core/skbuff.c:635 [] __kfree_skb+0x1d/0x20 net/core/skbuff.c:676 [] sk_wmem_free_skb include/net/sock.h:1447 [inline] [] tcp_write_queue_purge include/net/tcp.h:1460 [inline] [] tcp_connect_init net/ipv4/tcp_output.c:3122 [inline] [] tcp_connect+0xb24/0x30c0 net/ipv4/tcp_output.c:3261 [] tcp_v4_connect+0xf31/0x1890 net/ipv4/tcp_ipv4.c:246 [] __inet_stream_connect+0x2a9/0xc30 net/ipv4/af_inet.c:615 [] inet_stream_connect+0x55/0xa0 net/ipv4/af_inet.c:676 [] SYSC_connect+0x1b8/0x300 net/socket.c:1557 [] SyS_connect+0x24/0x30 net/socket.c:1538 [] entry_SYSCALL_64_fastpath+0x22/0x9e Syzkaller reproducer(): r0 = socket$packet(0x11, 0x3, 0x300) r1 = socket$inet_tcp(0x2, 0x1, 0x0) bind$inet(r1, &(0x7f0000000300)={0x2, 0x4e21, @multicast1}, 0x10) connect$inet(r1, &(0x7f0000000140)={0x2, 0x1000004e21, @loopback}, 0x10) recvmmsg(r1, &(0x7f0000001e40)=[{{0x0, 0x0, &(0x7f0000000100)=[{&(0x7f00000005c0)=""/88, 0x58}], 0x1}}], 0x1, 0x40000000, 0x0) sendto$inet(r1, &(0x7f0000000000)="e2f7ad5b661c761edf", 0x9, 0x8080, 0x0, 0x0) r2 = fcntl$dupfd(r1, 0x0, r0) connect$unix(r2, &(0x7f00000001c0)=@file={0x0, './file0\x00'}, 0x6e) C repro link: https://syzkaller.appspot.com/text?tag=ReproC&x=14db474f800000 This is because when tcp_connect_init call tcp_write_queue_purge, it will kfree all the skb in the write_queue, but the sk->sk_send_head forget to set NULL, then tcp_write_xmit try to send skb, which has freed in tcp_write_queue_purge, UAF happens. Signed-off-by: Mao Wenan --- include/net/tcp.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/net/tcp.h b/include/net/tcp.h index bf8a0dae977a..8f8aace28cf8 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1457,6 +1457,7 @@ static inline void tcp_write_queue_purge(struct sock *sk) while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) sk_wmem_free_skb(sk, skb); + sk->sk_send_head = NULL; sk_mem_reclaim(sk); tcp_clear_all_retrans_hints(tcp_sk(sk)); inet_csk(sk)->icsk_backoff = 0; -- 2.20.1