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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 21486C76186 for ; Tue, 30 Jul 2019 01:31:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED91A20679 for ; Tue, 30 Jul 2019 01:31:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730470AbfG3BbZ (ORCPT ); Mon, 29 Jul 2019 21:31:25 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:3237 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729473AbfG3BbY (ORCPT ); Mon, 29 Jul 2019 21:31:24 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 9DA0B8677B88E1F2180E; Tue, 30 Jul 2019 09:31:21 +0800 (CST) Received: from [127.0.0.1] (10.177.96.96) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.439.0; Tue, 30 Jul 2019 09:31:20 +0800 Subject: Re: [PATCH stable 4.9] tcp: reset sk_send_head in tcp_write_queue_purge To: Sasha Levin References: <20190729132108.162320-1-maowenan@huawei.com> <20190729153218.GA29162@sasha-vm> CC: , , , From: maowenan Message-ID: <29c1ee9c-4a5d-4f61-f526-85980185f0bd@huawei.com> Date: Tue, 30 Jul 2019 09:31:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20190729153218.GA29162@sasha-vm> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.96.96] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2019/7/29 23:32, Sasha Levin wrote: > On Mon, Jul 29, 2019 at 09:21:08PM +0800, Mao Wenan wrote: >> 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 > > So the "Fixes:" commit in the commit message is wrong? What's the actual > commit that this fixes? Upstream commit is 7f582b248d0a ("tcp: purge write queue in tcp_connect_init()") linux-4.4.y Fixes: 5bbe138a250e ("tcp: purge write queue in tcp_connect_init()") linux-4.9.y Fixes: 74a4c09d4b05 ("tcp: purge write queue in tcp_connect_init()") linux-4.14.y Fixes: a27fd7a8ed38 ("tcp: purge write queue upon RST") > > -- > Thanks, > Sasha > > . >