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=-5.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 17E73C10F27 for ; Wed, 11 Mar 2020 15:00:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E4F4E206C0 for ; Wed, 11 Mar 2020 15:00:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kk5K54fh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729928AbgCKPAm (ORCPT ); Wed, 11 Mar 2020 11:00:42 -0400 Received: from mail-vs1-f67.google.com ([209.85.217.67]:32888 "EHLO mail-vs1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729742AbgCKPAm (ORCPT ); Wed, 11 Mar 2020 11:00:42 -0400 Received: by mail-vs1-f67.google.com with SMTP id n27so1538851vsa.0; Wed, 11 Mar 2020 08:00:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Id7nxzKDmSxI0cxB6yaElDPLzg27V9lnZyiHS/FO3cA=; b=kk5K54fhbAGgKLS5pzQ5IBK/6e3411Mi/vQvsKgsNtPKuaPXlbKf/PzYtcLSiDVnHp /BEvBGQDspiC3/y9s1wFt85JYqEvuEr6Ulq/Z4UEs/6Sa5qJcVpdUY2Pj9BblfUo8wMS K+7V5iBp9NEbKD7WcK/Ed/w0tmoxXpnOEAD0sSh/89NBzOZXPPs/dZmzzixaS1UtUhxw 7vZxn0zMvG7/dlZ80GZC/ihGNABNrxELuSGjf+fUSjDY8TLbb6BSRAxoZmJ5aykPOXtp HhCD0DQfBCL3MAkpCx54tBjYfIkwCrEx/1inxtgRZc4Bawhz21c7tF5imQO5yoROlaES hHMw== 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=Id7nxzKDmSxI0cxB6yaElDPLzg27V9lnZyiHS/FO3cA=; b=MDeAgr5FF1uRGlCxxBQQXrLERxsFDpLuR/ILdr+AH7R8VhnAcPyMK78OjZi5lCFVMg JKONe+rORR+OyS4OtEXK/YB89pWkrTACkDM6+rmXxWjylKU+2eb2xJKC2epf8MGqhIZa EqmR7YGBolqTuI97h19LBNlv/WyB99IzfC4Fz1lpJurrtaRbbNeBGIZGHulWvYN3DGzn MLJvXSaOu+AwHXxMKYTJq3jXouuXfy7yVpF00KqIf94Pfn5GYBpnoSuyrae/QcN9VCv3 4vs+SGh4C0lIj5oDRE6kuxU0wOokbz91GPpMljZ3ZfjiaSg+ZC5faPoQ32Lv/Hrwfvwq uGxQ== X-Gm-Message-State: ANhLgQ3hOzZGYxnErRe0sAcd0u9LDKkYR6Z6ToUUZ91nbyYLZ3Zv5FNN Jr7CzIyUDZMkjwd4IMg4b2nq8Ia5GfXPqLvRlEk= X-Google-Smtp-Source: ADFU+vv2eJRjNaYGv0DYhFYkPBmmDTYaOnz/JeuA1Du+FLPVAUHXTCfm+H4I//Ti2O1te8g82zroRYnrkf1z+R50+5A= X-Received: by 2002:a67:7182:: with SMTP id m124mr2269349vsc.150.1583938838979; Wed, 11 Mar 2020 08:00:38 -0700 (PDT) MIME-Version: 1.0 References: <00000000000088452f05a07621d2@google.com> In-Reply-To: <00000000000088452f05a07621d2@google.com> From: Qiujun Huang Date: Wed, 11 Mar 2020 23:00:27 +0800 Message-ID: Subject: Re: WARNING: refcount bug in sctp_wfree To: syzbot , vyasevich@gmail.com Cc: davem@davemloft.net, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-sctp@vger.kernel.org, marcelo.leitner@gmail.com, netdev@vger.kernel.org, nhorman@tuxdriver.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org sctp_wfree ->refcount_sub_and_test(sizeof(struct sctp_chunk), &sk->sk_wmem_alloc) sctp_wfree will sub sizeof(struct sctp_chunk) for every skb. So could we add the extra size for gso segment ? --- a/net/sctp/output.c +++ b/net/sctp/output.c @@ -398,7 +398,8 @@ static void sctp_packet_gso_append(struct sk_buff *head, struct sk_buff *skb) head->truesize += skb->truesize; head->data_len += skb->len; head->len += skb->len; - refcount_add(skb->truesize, &head->sk->sk_wmem_alloc); + refcount_add(skb->truesize + sizeof(struct sctp_chunk), + &head->sk->sk_wmem_alloc); __skb_header_release(skb); On Tue, Mar 10, 2020 at 9:36 AM syzbot wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: 2c523b34 Linux 5.6-rc5 > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=155a5f29e00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=a5295e161cd85b82 > dashboard link: https://syzkaller.appspot.com/bug?extid=cea71eec5d6de256d54d > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=164b5181e00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=166dd70de00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+cea71eec5d6de256d54d@syzkaller.appspotmail.com > > ------------[ cut here ]------------ > refcount_t: underflow; use-after-free. > WARNING: CPU: 1 PID: 8668 at lib/refcount.c:28 refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28 > Kernel panic - not syncing: panic_on_warn set ... > CPU: 1 PID: 8668 Comm: syz-executor779 Not tainted 5.6.0-rc5-syzkaller #0 > 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+0x1e9/0x30e lib/dump_stack.c:118 > panic+0x264/0x7a0 kernel/panic.c:221 > __warn+0x209/0x210 kernel/panic.c:582 > report_bug+0x1ac/0x2d0 lib/bug.c:195 > fixup_bug arch/x86/kernel/traps.c:174 [inline] > do_error_trap+0xca/0x1c0 arch/x86/kernel/traps.c:267 > do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286 > invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 > RIP: 0010:refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28 > Code: c7 e4 ff d0 88 31 c0 e8 23 20 b3 fd 0f 0b eb 85 e8 8a 4a e0 fd c6 05 ff 70 b1 05 01 48 c7 c7 10 00 d1 88 31 c0 e8 05 20 b3 fd <0f> 0b e9 64 ff ff ff e8 69 4a e0 fd c6 05 df 70 b1 05 01 48 c7 c7 > RSP: 0018:ffffc90001f577d0 EFLAGS: 00010246 > RAX: 8c9c9070bbb4e500 RBX: 0000000000000003 RCX: ffff8880938a63c0 > RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 > RBP: 0000000000000003 R08: ffffffff815e16e6 R09: fffffbfff15db92a > R10: fffffbfff15db92a R11: 0000000000000000 R12: dffffc0000000000 > R13: ffff88809de82000 R14: ffff8880a89237c0 R15: 1ffff11013be52b0 > sctp_wfree+0x3b1/0x710 net/sctp/socket.c:9111 > skb_release_head_state+0xfb/0x210 net/core/skbuff.c:651 > skb_release_all net/core/skbuff.c:662 [inline] > __kfree_skb+0x22/0x1c0 net/core/skbuff.c:678 > sctp_chunk_destroy net/sctp/sm_make_chunk.c:1454 [inline] > sctp_chunk_put+0x17b/0x200 net/sctp/sm_make_chunk.c:1481 > __sctp_outq_teardown+0x80a/0x9d0 net/sctp/outqueue.c:257 > sctp_association_free+0x21e/0x7c0 net/sctp/associola.c:339 > sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:930 [inline] > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1318 [inline] > sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline] > sctp_do_sm+0x3c01/0x5560 net/sctp/sm_sideeffect.c:1156 > sctp_primitive_ABORT+0x93/0xc0 net/sctp/primitive.c:104 > sctp_close+0x231/0x770 net/sctp/socket.c:1512 > inet_release+0x135/0x180 net/ipv4/af_inet.c:427 > __sock_release net/socket.c:605 [inline] > sock_close+0xd8/0x260 net/socket.c:1283 > __fput+0x2d8/0x730 fs/file_table.c:280 > task_work_run+0x176/0x1b0 kernel/task_work.c:113 > exit_task_work include/linux/task_work.h:22 [inline] > do_exit+0x5ef/0x1f80 kernel/exit.c:801 > do_group_exit+0x15e/0x2c0 kernel/exit.c:899 > __do_sys_exit_group+0x13/0x20 kernel/exit.c:910 > __se_sys_exit_group+0x10/0x10 kernel/exit.c:908 > __x64_sys_exit_group+0x37/0x40 kernel/exit.c:908 > do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x43ef98 > Code: Bad RIP value. > RSP: 002b:00007ffcc7e7c398 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ef98 > RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 > RBP: 00000000004be7a8 R08: 00000000000000e7 R09: ffffffffffffffd0 > R10: 000000002059aff8 R11: 0000000000000246 R12: 0000000000000001 > R13: 00000000006d01a0 R14: 0000000000000000 R15: 0000000000000000 > Kernel Offset: disabled > Rebooting in 86400 seconds.. > > > --- > 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#status for how to communicate with syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches