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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 6A900C76193 for ; Mon, 29 Jul 2019 13:17:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40EE72070B for ; Mon, 29 Jul 2019 13:17:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388066AbfG2NRq (ORCPT ); Mon, 29 Jul 2019 09:17:46 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:52848 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387920AbfG2NRp (ORCPT ); Mon, 29 Jul 2019 09:17:45 -0400 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id CF713298BD40AEA61126; Mon, 29 Jul 2019 21:17:42 +0800 (CST) Received: from localhost.localdomain.localdomain (10.175.113.25) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.439.0; Mon, 29 Jul 2019 21:17:39 +0800 From: Mao Wenan To: , CC: , Subject: [PATCH stable 4.4] tcp: reset sk_send_head in tcp_write_queue_purge Date: Mon, 29 Jul 2019 21:22:42 +0800 Message-ID: <20190729132242.162505-1-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: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Soheil Hassas Yeganeh tcp_write_queue_purge clears all the SKBs in the write queue but does not reset the sk_send_head. As a result, we can have a NULL pointer dereference anywhere that we use tcp_send_head instead of the tcp_write_queue_tail. For example, after a27fd7a8ed38 (tcp: purge write queue upon RST), we can purge the write queue on RST. Prior to 75c119afe14f (tcp: implement rb-tree based retransmit queue), tcp_push will only check tcp_send_head and then accesses tcp_write_queue_tail to send the actual SKB. As a result, it will dereference a NULL pointer. This has been reported twice for 4.14 where we don't have 75c119afe14f: By Timofey Titovets: [ 422.081094] BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 [ 422.081254] IP: tcp_push+0x42/0x110 [ 422.081314] PGD 0 P4D 0 [ 422.081364] Oops: 0002 [#1] SMP PTI By Yongjian Xu: BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 IP: tcp_push+0x48/0x120 PGD 80000007ff77b067 P4D 80000007ff77b067 PUD 7fd989067 PMD 0 Oops: 0002 [#18] SMP PTI Modules linked in: tcp_diag inet_diag tcp_bbr sch_fq iTCO_wdt iTCO_vendor_support pcspkr ixgbe mdio i2c_i801 lpc_ich joydev input_leds shpchp e1000e igb dca ptp pps_core hwmon mei_me mei ipmi_si ipmi_msghandler sg ses scsi_transport_sas enclosure ext4 jbd2 mbcache sd_mod ahci libahci megaraid_sas wmi ast ttm dm_mirror dm_region_hash dm_log dm_mod dax CPU: 6 PID: 14156 Comm: [ET_NET 6] Tainted: G D 4.14.26-1.el6.x86_64 #1 Hardware name: LENOVO ThinkServer RD440 /ThinkServer RD440, BIOS A0TS80A 09/22/2014 task: ffff8807d78d8140 task.stack: ffffc9000e944000 RIP: 0010:tcp_push+0x48/0x120 RSP: 0018:ffffc9000e947a88 EFLAGS: 00010246 RAX: 00000000000005b4 RBX: ffff880f7cce9c00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000040 RDI: ffff8807d00f5000 RBP: ffffc9000e947aa8 R08: 0000000000001c84 R09: 0000000000000000 R10: ffff8807d00f5158 R11: 0000000000000000 R12: ffff8807d00f5000 R13: 0000000000000020 R14: 00000000000256d4 R15: 0000000000000000 FS: 00007f5916de9700(0000) GS:ffff88107fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000038 CR3: 00000007f8226004 CR4: 00000000001606e0 Call Trace: tcp_sendmsg_locked+0x33d/0xe50 tcp_sendmsg+0x37/0x60 inet_sendmsg+0x39/0xc0 sock_sendmsg+0x49/0x60 sock_write_iter+0xb6/0x100 do_iter_readv_writev+0xec/0x130 ? rw_verify_area+0x49/0xb0 do_iter_write+0x97/0xd0 vfs_writev+0x7e/0xe0 ? __wake_up_common_lock+0x80/0xa0 ? __fget_light+0x2c/0x70 ? __do_page_fault+0x1e7/0x530 do_writev+0x60/0xf0 ? inet_shutdown+0xac/0x110 SyS_writev+0x10/0x20 do_syscall_64+0x6f/0x140 ? prepare_exit_to_usermode+0x8b/0xa0 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 RIP: 0033:0x3135ce0c57 RSP: 002b:00007f5916de4b00 EFLAGS: 00000293 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000003135ce0c57 RDX: 0000000000000002 RSI: 00007f5916de4b90 RDI: 000000000000606f RBP: 0000000000000000 R08: 0000000000000000 R09: 00007f5916de8c38 R10: 0000000000000000 R11: 0000000000000293 R12: 00000000000464cc R13: 00007f5916de8c30 R14: 00007f58d8bef080 R15: 0000000000000002 Code: 48 8b 97 60 01 00 00 4c 8d 97 58 01 00 00 41 b9 00 00 00 00 41 89 f3 4c 39 d2 49 0f 44 d1 41 81 e3 00 80 00 00 0f 85 b0 00 00 00 <80> 4a 38 08 44 8b 8f 74 06 00 00 44 89 8f 7c 06 00 00 83 e6 01 RIP: tcp_push+0x48/0x120 RSP: ffffc9000e947a88 CR2: 0000000000000038 ---[ end trace 8d545c2e93515549 ]--- There is other scenario which found in stable 4.4: Allocated: [] __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 Freed: [] __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 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 [] 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 stable 4.4 and stable 4.9 don't have the commit abb4a8b870b5 ("tcp: purge write queue upon RST") which is referred in dbbf2d1e4077, in tcp_connect_init, it calls tcp_write_queue_purge, and does not reset sk_send_head, then UAF. stable 4.14 have the commit abb4a8b870b5 ("tcp: purge write queue upon RST"), in tcp_reset, it calls tcp_write_queue_purge(sk), and does not reset sk_send_head, then UAF. So this patch can be used to fix stable 4.4 and 4.9. Fixes: a27fd7a8ed38 (tcp: purge write queue upon RST) Reported-by: Timofey Titovets Reported-by: Yongjian Xu Signed-off-by: Eric Dumazet Signed-off-by: Soheil Hassas Yeganeh Tested-by: Yongjian Xu Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman Signed-off-by: Mao Wenan --- include/net/tcp.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index bf8a0dae977a..77438a8406ec 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1443,6 +1443,11 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, void tcp_fastopen_init_key_once(bool publish); #define TCP_FASTOPEN_KEY_LENGTH 16 +static inline void tcp_init_send_head(struct sock *sk) +{ + sk->sk_send_head = NULL; +} + /* Fastopen key context */ struct tcp_fastopen_context { struct crypto_cipher *tfm; @@ -1459,6 +1464,7 @@ static inline void tcp_write_queue_purge(struct sock *sk) sk_wmem_free_skb(sk, skb); sk_mem_reclaim(sk); tcp_clear_all_retrans_hints(tcp_sk(sk)); + tcp_init_send_head(sk); inet_csk(sk)->icsk_backoff = 0; } @@ -1520,11 +1526,6 @@ static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unli tcp_sk(sk)->highest_sack = NULL; } -static inline void tcp_init_send_head(struct sock *sk) -{ - sk->sk_send_head = NULL; -} - static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) { __skb_queue_tail(&sk->sk_write_queue, skb); -- 2.20.1