From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 299C632721C for ; Wed, 26 Nov 2025 12:22:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764159760; cv=none; b=czkEdBajk9jg3oU1ek7/4iKT/2VIVfaj7FiQRwENArq5R5brW2wekIIWZyMr/Dv27dhszSXDX8+Q6pVPNmS0KLdtouuBIo2KrOZuwMHdbE4pGWsUgM638egB/Z9N3Cmz8IpoXxb/Tv4k65bm0ZOI++zteoGNz9mlcpHUBgmAGaM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764159760; c=relaxed/simple; bh=WSgIh+6C/7QuvVPLGPe3Pa03Ajb2EKyzl9nCFSjmaQg=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=sSy861tEG8sEtE+En0IiPTdlTMzVIQs+Pi97P9KyPF7VKwAhcAffbaxf8CjH9eXww7QZmWHui2ZEBV8+vuHgf6k1uRFmRIGPlCZgIcSu4DmdZ5e18Hth22AEMabLZvR2UIHMPWvaPuksOQmTHYyXEQBeXNsEH9GFaOkK04+gShY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QmuwWQJx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QmuwWQJx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0998FC16AAE; Wed, 26 Nov 2025 12:22:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764159760; bh=WSgIh+6C/7QuvVPLGPe3Pa03Ajb2EKyzl9nCFSjmaQg=; h=Date:Subject:To:References:From:In-Reply-To:From; b=QmuwWQJxrDqAyY6J9uQN8aJvvS9rBbgPI8BSHXw9TtwAXEo/zYpJJffqoWDCB1kVw /WCt3EXZDT7CdaWZdvs3lACqCskmHOwNqWGZg7ASruvhq/N5UY9GOS/6W6JrC5YdM/ MUzl/pllCs9gdheUMg4OCH63iSEV9PeSP+hBuWKVdiHNYH2WZNmOnSJOjVj14dEYS2 L0VtgZ/ucG76jW7G6COPFazAHRmIs2wYW9/LloorVBdkJboh28DWqr5OhMHXryMQrD GD6mSM4t7Uw47T9A6ymqdN8+oowv+ySXG2z1aW2bk9fGUIWB6OvOripKSrl7xMKmp3 Qb262T/2bQ6UQ== Message-ID: <5336d822-a26f-495c-9f35-1c1aa140a715@kernel.org> Date: Wed, 26 Nov 2025 13:22:36 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [syzbot] [net?] divide error in __tcp_select_window (4) Content-Language: en-GB, fr-BE To: syzbot , linux-kernel@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com References: <6926f074.a70a0220.d98e3.00d4.GAE@google.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hello, On 26/11/2025 13:20, syzbot wrote: > Hello, > > syzbot has tested the proposed patch but the reproducer is still triggering an issue: > divide error in __tcp_select_window > > RSP: 002b:00007f86321dd038 EFLAGS: 00000246 ORIG_RAX: 000000000000002c > RAX: ffffffffffffffda RBX: 00007f86315e5fa0 RCX: 00007f863138f749 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 > RBP: 00007f86321dd090 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 > R13: 00007f86315e6038 R14: 00007f86315e5fa0 R15: 00007ffd93c62a18 > > Oops: divide error: 0000 [#1] SMP KASAN PTI > CPU: 1 UID: 0 PID: 6439 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 > RIP: 0010:__tcp_select_window+0x824/0x1320 net/ipv4/tcp_output.c:3336 > Code: ff ff ff 44 89 f1 d3 e0 89 c1 f7 d1 41 01 cc 41 21 c4 e9 a9 00 00 00 e8 da 10 01 f8 e9 9c 00 00 00 e8 d0 10 01 f8 44 89 e0 99 7c 24 1c 41 29 d4 48 bb 00 00 00 00 00 fc ff df e9 80 00 00 00 > RSP: 0018:ffffc900030a7640 EFLAGS: 00010293 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8880258abc80 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: ffffc900030a7730 R08: ffff8880310e8dc3 R09: 1ffff1100621d1b8 > R10: dffffc0000000000 R11: ffffed100621d1b9 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > FS: 00007f86321dd6c0(0000) GS:ffff888126235000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000200000000180 CR3: 000000007e366000 CR4: 00000000003526f0 > Call Trace: > > tcp_select_window net/ipv4/tcp_output.c:281 [inline] > __tcp_transmit_skb+0xbc7/0x3aa0 net/ipv4/tcp_output.c:1568 > tcp_transmit_skb net/ipv4/tcp_output.c:1649 [inline] > tcp_send_active_reset+0x2d1/0x5b0 net/ipv4/tcp_output.c:3836 > mptcp_do_fastclose+0x286/0x390 net/mptcp/protocol.c:2896 > mptcp_disconnect+0x238/0x730 net/mptcp/protocol.c:3380 > mptcp_sendmsg_fastopen+0x2f8/0x580 net/mptcp/protocol.c:1801 Indeed, my bad, I missed this: it is a different issue involving TFO (too many 'fast' :) ). A different fix than the one from Paolo -- like the one sent by Kuniyuki -- is still needed. Cheers, Matt -- Sponsored by the NGI0 Core fund.