linux-kernel - Re: [syzbot] [net?] divide error in __tcp_select

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Message-ID: <6926e9be.a70a0220.d98e3.00d2.GAE@google.com>
Date: Wed, 26 Nov 2025 03:51:26 -0800
From: syzbot <syzbot+3a92d359bc2ec6255a33@...kaller.appspotmail.com>
To: matttbe@...nel.org
Cc: matttbe@...nel.org, pabeni@...hat.com, syzkaller-bugs@...glegroups.com, 
	linux-kernel@...r.kernel.org
Subject: Re: [syzbot] [net?] divide error in __tcp_select_window (4)

> Hello,
>
> (+cc Paolo)
>
> On 26/11/2025 12:28, Matthieu Baerts wrote:
>> Hello,
>> 
>> (Without other ML's to test a different fix)
>> 
>> On 25/11/2025 20:50, syzbot wrote:
>>> Hello,
>>>
>>> syzbot found the following issue on:
>>>
>>> HEAD commit:    e2c20036a887 Merge branch 'devlink-net-mlx5-implement-swp_..
>>> git tree:       net-next
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1164c484580000
>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=a881ccda32df4e75
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=3a92d359bc2ec6255a33
>>> compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
>>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13f8fa12580000
>>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=113a5a12580000
>>>
>>> Downloadable assets:
>>> disk image: https://storage.googleapis.com/syzbot-assets/07279e689a07/disk-e2c20036.raw.xz
>>> vmlinux: https://storage.googleapis.com/syzbot-assets/b13e2e59c1ed/vmlinux-e2c20036.xz
>>> kernel image: https://storage.googleapis.com/syzbot-assets/f6f519394597/bzImage-e2c20036.xz
>>>
>>> The issue was bisected to:
>>>
>>> commit ae155060247be8dcae3802a95bd1bdf93ab3215d
>>> Author: Paolo Abeni <pabeni@...hat.com>
>>> Date:   Tue Nov 18 07:20:24 2025 +0000
>>>
>>>     mptcp: fix duplicate reset on fastclose
>>>
>>> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11f698b4580000
>>> final oops:     https://syzkaller.appspot.com/x/report.txt?x=13f698b4580000
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=15f698b4580000
>>>
>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>>> Reported-by: syzbot+3a92d359bc2ec6255a33@...kaller.appspotmail.com
>>> Fixes: ae155060247b ("mptcp: fix duplicate reset on fastclose")
>> 
>> I *think* this issue might have been fixed by another patch that has
>> been sent recently, see "mptcp: clear scheduled subflows on retransmit":
>> 
>> 
>> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/matttbe/net-next.git b4/net-mptcp-clear-sched-rtx
>
>
> Mmh, sorry for the noise, I just noticed the reproducers were apparently
> only working on top of net-next, and my branch was on top of 'net'.
> Sending the patch with net-next as base then.
>
> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git

"Cheers," does not look like a valid git branch or commit.

>
> Cheers,
> Matt
> -- 
> Sponsored by the NGI0 Core fund.