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=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham 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 0CB5EC282C2 for ; Wed, 13 Feb 2019 14:00:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B65C320836 for ; Wed, 13 Feb 2019 14:00:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Zp4JPMDf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391117AbfBMOAw (ORCPT ); Wed, 13 Feb 2019 09:00:52 -0500 Received: from mail-it1-f196.google.com ([209.85.166.196]:34227 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728701AbfBMOAv (ORCPT ); Wed, 13 Feb 2019 09:00:51 -0500 Received: by mail-it1-f196.google.com with SMTP id j17so1832255ita.1 for ; Wed, 13 Feb 2019 06:00:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=ut6hpockqNHNIdrlsRn3m1rhLnYQQcmpxwFwHoaM8L8=; b=Zp4JPMDfv7Si5Lot96RlaKrN57nDSoJu3HB4364aDyAMJULII2NxLDDAkMAS8tXNB0 QbAcxgGutu8P6flW1my+zbcxWXSQ+gJskaBHO763j0egDcHzlS7vdJ2zAF+nXCSmt6bE GF2k4T0yGGQFe0Bv/HMtmQAVJqIKv72/QTByUZsujdo2+jQilwJm+U6IneCGyx+KONF2 ySVaCial7IiXBEVHsX/EyTYqBc3RxOpf8bATrEDmDR+e5QsevBgcJMPAEc+Xk3N6S5gy dBfbjhlo6u+/1FD4afz9vPVobUe7Ubvx1IelrAXUXjawlsBjl8J22yzZhrXP/2kPReOM zKqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ut6hpockqNHNIdrlsRn3m1rhLnYQQcmpxwFwHoaM8L8=; b=ssGO3jM9igJcN+Khos7nP6zuiicEhfoBRW99qXQ3hpJ0pMRLqD36vHRT2ZkzWhKG9A QnQK5fcbKGbGHHWHAFlP7g2UZQfo6Ms1DFILvpzqHUuxUXu1JhCzl9tV6chQzYTXpWem 37/DMFUlBxd4lnl87m5na2I1dGEc9YgXsMWsfe9kgVQQ8sraNGsh9xJqLRm5jrO2muJ8 +Bu6CaI6gD8MgXhwxlKI1szIRhdnJGGwmgH/mBnRR9ZesY7tnLv0xg7jTH7F4COOsR4S 3gGLjCps7MzSmQGeEfkd9uuFk+jiWnaDKcwHJXxcNLhChdczxXLnpWrZV4fJo89eBB7C THXQ== X-Gm-Message-State: AHQUAuYio+U/l1Evle16aJk34Z82oIHorP60Sm/kvwoSc+2aSYbdYBFP 6twUk9Qg2XoFROfoZg/rNm3XqvG/NvviboBnsFuEzw== X-Google-Smtp-Source: AHgI3IbfpSmQd15AljP67dF/eQ+OuOHoW92mi0zQslvmsgY826XmZPhcJjn+IDabz386KrY7LgsPl8SAIxLb23pnh3Y= X-Received: by 2002:a5d:84c3:: with SMTP id z3mr362086ior.11.1550066450285; Wed, 13 Feb 2019 06:00:50 -0800 (PST) MIME-Version: 1.0 References: <0000000000002015db0581b71858@google.com> <20190213135157.GJ10665@localhost.localdomain> In-Reply-To: <20190213135157.GJ10665@localhost.localdomain> From: Dmitry Vyukov Date: Wed, 13 Feb 2019 15:00:37 +0100 Message-ID: Subject: Re: KASAN: use-after-free Read in sctp_outq_tail To: Marcelo Ricardo Leitner Cc: Xin Long , syzbot , davem , LKML , linux-sctp@vger.kernel.org, network dev , Neil Horman , syzkaller-bugs , Vlad Yasevich Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 13, 2019 at 2:52 PM Marcelo Ricardo Leitner wrote: > > On Wed, Feb 13, 2019 at 12:35:56PM +0800, Xin Long wrote: > > On Wed, Feb 13, 2019 at 4:00 AM syzbot > > wrote: > > > > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: d4104460aec1 Add linux-next specific files for 20190211 > > > git tree: linux-next > > > console output: https://syzkaller.appspot.com/x/log.txt?x=14140124c00000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=c8a112d3b0d6719b > > > dashboard link: https://syzkaller.appspot.com/bug?extid=7823fa3f3e2d69341ea8 > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > Reported-by: syzbot+7823fa3f3e2d69341ea8@syzkaller.appspotmail.com > > > > > > ================================================================== > > > BUG: KASAN: use-after-free in list_add_tail include/linux/list.h:93 [inline] > > > BUG: KASAN: use-after-free in sctp_outq_tail_data net/sctp/outqueue.c:105 > > > [inline] > > > BUG: KASAN: use-after-free in sctp_outq_tail+0x816/0x930 > > > net/sctp/outqueue.c:313 > > > Read of size 8 at addr ffff88807b19a7b8 by task syz-executor.0/30745 > > I think https://patchwork.ozlabs.org/patch/1040500/ will fix this. > > I don't think so. Seems it will switch from use-after-free to NULL deref > instead with that patch. Let's unmark it as fixed for now then so that syzbot does not close it prematurely #syz fix: see discussion on the report email thread > > > CPU: 1 PID: 30745 Comm: syz-executor.0 Not tainted 5.0.0-rc5-next-20190211 > > > #32 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > > Google 01/01/2011 > > > Call Trace: > > > __dump_stack lib/dump_stack.c:77 [inline] > > > dump_stack+0x172/0x1f0 lib/dump_stack.c:113 > > > print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 > > > kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 > > > __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 > > > list_add_tail include/linux/list.h:93 [inline] > > > sctp_outq_tail_data net/sctp/outqueue.c:105 [inline] > > > sctp_outq_tail+0x816/0x930 net/sctp/outqueue.c:313 > > > sctp_cmd_send_msg net/sctp/sm_sideeffect.c:1109 [inline] > > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1784 [inline] > > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline] > > > sctp_do_sm+0x68e/0x5380 net/sctp/sm_sideeffect.c:1191 > > > sctp_primitive_SEND+0xa0/0xd0 net/sctp/primitive.c:178 > > > sctp_sendmsg_to_asoc+0xa63/0x17b0 net/sctp/socket.c:1955 > > sctp_sendmsg_to_asoc() > ... > if (sinfo->sinfo_stream >= asoc->stream.outcnt) { > err = -EINVAL; > goto err; > } > > if (unlikely(!SCTP_SO(&asoc->stream, sinfo->sinfo_stream)->ext)) { > ... > > It should have aborted even if an old ->ext was still there because > outcnt is correctly updated. So somehow outcnt was wrong here. > > sctp_stream_init() > ... > /* Filter out chunks queued on streams that won't exist anymore */ > sched->unsched_all(stream); > sctp_stream_outq_migrate(stream, NULL, outcnt); <--- [A] > sched->sched_all(stream); > > ret = sctp_stream_alloc_out(stream, outcnt, gfp); <--- [B] > if (ret) > goto out; > > stream->outcnt = outcnt; <--- [C] > ... > > We have a problem here because [A] is freeing ->ext, but [B] can fail (ENOMEM), > which would lead it to not update outcnt in [C] even after the > changes already performed in [A]. > > It should handle the freeing of ->ext in sctp_stream_alloc_out() > instead, or allocate the flexarray earlier (so it can bail out before > freeing stuff). > > > > sctp_sendmsg+0x10a9/0x17e0 net/sctp/socket.c:2113 > > > inet_sendmsg+0x147/0x5d0 net/ipv4/af_inet.c:798 > > > sock_sendmsg_nosec net/socket.c:621 [inline] > > > sock_sendmsg+0xdd/0x130 net/socket.c:631 > > > ___sys_sendmsg+0x806/0x930 net/socket.c:2136 > > > __sys_sendmsg+0x105/0x1d0 net/socket.c:2174 > > > __do_sys_sendmsg net/socket.c:2183 [inline] > > > __se_sys_sendmsg net/socket.c:2181 [inline] > > > __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2181 > > > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > RIP: 0033:0x457e39 > > > Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 > > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff > > > ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > > > RSP: 002b:00007fa9b8630c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e > > > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457e39 > > > RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000003 > > > RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 > > > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa9b86316d4 > > > R13: 00000000004c4e2b R14: 00000000004d8ab8 R15: 00000000ffffffff > > > > > > Allocated by task 30745: > > > save_stack+0x45/0xd0 mm/kasan/common.c:75 > > > set_track mm/kasan/common.c:87 [inline] > > > __kasan_kmalloc mm/kasan/common.c:498 [inline] > > > __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:471 > > > kasan_kmalloc+0x9/0x10 mm/kasan/common.c:506 > > > kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3615 > > > kmalloc include/linux/slab.h:548 [inline] > > > kzalloc include/linux/slab.h:743 [inline] > > > sctp_stream_init_ext+0x51/0x110 net/sctp/stream.c:172 > > > sctp_sendmsg_to_asoc+0x1273/0x17b0 net/sctp/socket.c:1896 > > > sctp_sendmsg+0x10a9/0x17e0 net/sctp/socket.c:2113 > > > inet_sendmsg+0x147/0x5d0 net/ipv4/af_inet.c:798 > > > sock_sendmsg_nosec net/socket.c:621 [inline] > > > sock_sendmsg+0xdd/0x130 net/socket.c:631 > > > ___sys_sendmsg+0x806/0x930 net/socket.c:2136 > > > __sys_sendmsg+0x105/0x1d0 net/socket.c:2174 > > > __do_sys_sendmsg net/socket.c:2183 [inline] > > > __se_sys_sendmsg net/socket.c:2181 [inline] > > > __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2181 > > > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > > > Freed by task 30745: > > > save_stack+0x45/0xd0 mm/kasan/common.c:75 > > > set_track mm/kasan/common.c:87 [inline] > > > __kasan_slab_free+0x102/0x150 mm/kasan/common.c:460 > > > kasan_slab_free+0xe/0x10 mm/kasan/common.c:468 > > > __cache_free mm/slab.c:3491 [inline] > > > kfree+0xcf/0x230 mm/slab.c:3816 > > > sctp_stream_outq_migrate+0x3e6/0x540 net/sctp/stream.c:88 > > > sctp_stream_init+0xbc/0x410 net/sctp/stream.c:139 > > > sctp_process_init+0x21c3/0x2b20 net/sctp/sm_make_chunk.c:2466 > > > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline] > > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline] > > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline] > > > sctp_do_sm+0x3145/0x5380 net/sctp/sm_sideeffect.c:1191 > > > sctp_assoc_bh_rcv+0x343/0x660 net/sctp/associola.c:1074 > > > sctp_inq_push+0x1ea/0x290 net/sctp/inqueue.c:95 > > > sctp_backlog_rcv+0x196/0xbe0 net/sctp/input.c:354 > > > sk_backlog_rcv include/net/sock.h:937 [inline] > > > __release_sock+0x12e/0x3a0 net/core/sock.c:2379 > > > release_sock+0x59/0x1c0 net/core/sock.c:2895 > > > sctp_wait_for_connect+0x316/0x540 net/sctp/socket.c:8998 > > > sctp_sendmsg_to_asoc+0x13e3/0x17b0 net/sctp/socket.c:1967 > > > sctp_sendmsg+0x10a9/0x17e0 net/sctp/socket.c:2113 > > > inet_sendmsg+0x147/0x5d0 net/ipv4/af_inet.c:798 > > > sock_sendmsg_nosec net/socket.c:621 [inline] > > > sock_sendmsg+0xdd/0x130 net/socket.c:631 > > > ___sys_sendmsg+0x806/0x930 net/socket.c:2136 > > > __sys_sendmsg+0x105/0x1d0 net/socket.c:2174 > > > __do_sys_sendmsg net/socket.c:2183 [inline] > > > __se_sys_sendmsg net/socket.c:2181 [inline] > > > __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2181 > > > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > > > The buggy address belongs to the object at ffff88807b19a780 > > > which belongs to the cache kmalloc-96 of size 96 > > > The buggy address is located 56 bytes inside of > > > 96-byte region [ffff88807b19a780, ffff88807b19a7e0) > > > The buggy address belongs to the page: > > > page:ffffea0001ec6680 count:1 mapcount:0 mapping:ffff88812c3f04c0 > > > index:0xffff88807b19a800 > > > flags: 0x1fffc0000000200(slab) > > > raw: 01fffc0000000200 ffffea000262acc8 ffffea0001448348 ffff88812c3f04c0 > > > raw: ffff88807b19a800 ffff88807b19a000 000000010000001d 0000000000000000 > > > page dumped because: kasan: bad access detected > > > > > > Memory state around the buggy address: > > > ffff88807b19a680: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > > > ffff88807b19a700: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > > > > ffff88807b19a780: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > > > ^ > > > ffff88807b19a800: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > > > ffff88807b19a880: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > > > ================================================================== > > > > > > > > > --- > > > This bug is generated by a bot. It may contain errors. > > > See https://goo.gl/tpsmEJ for more information about syzbot. > > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > > > syzbot will keep track of this bug report. See: > > > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with > > > syzbot. > > > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20190213135157.GJ10665%40localhost.localdomain. > For more options, visit https://groups.google.com/d/optout.