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

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Message-ID: <6926e47f.a70a0220.d98e3.00d1.GAE@google.com>
Date: Wed, 26 Nov 2025 03:29:03 -0800
From: syzbot <syzbot+3a92d359bc2ec6255a33@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org
Subject: Forwarded: Re: [syzbot] [net?] divide error in __tcp_select_window (4)

For archival purposes, forwarding an incoming command email to
linux-kernel@...r.kernel.org.

***

Subject: Re: [syzbot] [net?] divide error in __tcp_select_window (4)
Author: matttbe@...nel.org

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


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