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 0BC66246BD8; Mon, 17 Nov 2025 10:15:11 +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=1763374513; cv=none; b=lS+8w4XQGd1rnFljxmIRUR88MD5J399xdtLc/YPdTr9atIq+4R021Ie8Jor3c2dOfJ70XHTKFFs+PUi8/2UgBL2GEXOYZmDtJ7RGYxxH9PqZ0fLe/Jjs7yFOdH7SZVEO9OEvg7mgeNy8vyTsnbebdwTUBq/xTOMG0z0019PDKEo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763374513; c=relaxed/simple; bh=XVbbG4imr6HzX5iLiSFcVh0dofyN7KdappAN0sNfiR4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rBi45E2r8jhmLP4LMYl+RZ0O1JVNAIwDKJXqilrBbwOEVtcdY6oEn1/mFF5BjcqAU+SzsURSXlFylWCqnk7sQGRBFHV7oz9NS6CzmcAre+FPV44LD5hhG35Av2dvsrmvbhuyW5ox+wGEx1R16Dm315RE0jE/kV52hLlX5SuX5k8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VOmlPux6; 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="VOmlPux6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F523C113D0; Mon, 17 Nov 2025 10:15:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763374511; bh=XVbbG4imr6HzX5iLiSFcVh0dofyN7KdappAN0sNfiR4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=VOmlPux6bfpytdmEbJP38bvwwEWuXzCkA/bkNlhMWeXZs48XXitKZHaDMR/bU8pZs 0M//2Q4KvBCCtqZuxtbJXQveQeLU2OKfh3sH/BGaAijp252rZy8eobu1mTEvPUGcrv zIDXL/4wISnQHMAmFvS8z5B0Fw1hFtvTbm9RjrEkEKfMhb5e3Jh/UhhJMhVDgRRg/j uHicaFE6SfciSoltS+wfcWooRXgDGHVFr0H6uMZ1YvTAb/zFoOoVfiuZLbwjgKHAkV ny4HY72lBvq9N5fTeCOYF4d4oj2Tz22jOjMP1pzXounvApNFlxJuoU5U3Dxov/QdSb B9Wo9/lV9oZaQ== Message-ID: Date: Mon, 17 Nov 2025 11:15:06 +0100 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 net] mptcp: fix a race in mptcp_pm_del_add_timer() Content-Language: en-GB, fr-BE To: Eric Dumazet Cc: Mat Martineau , Geliang Tang , Florian Westphal , netdev@vger.kernel.org, eric.dumazet@gmail.com, syzbot+2a6fbf0f0530375968df@syzkaller.appspotmail.com, Geliang Tang , MPTCP Linux , "David S . Miller" , Jakub Kicinski , Paolo Abeni References: <20251117100745.1913963-1-edumazet@google.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; keydata= xsFNBFXj+ekBEADxVr99p2guPcqHFeI/JcFxls6KibzyZD5TQTyfuYlzEp7C7A9swoK5iCvf YBNdx5Xl74NLSgx6y/1NiMQGuKeu+2BmtnkiGxBNanfXcnl4L4Lzz+iXBvvbtCbynnnqDDqU c7SPFMpMesgpcu1xFt0F6bcxE+0ojRtSCZ5HDElKlHJNYtD1uwY4UYVGWUGCF/+cY1YLmtfb WdNb/SFo+Mp0HItfBC12qtDIXYvbfNUGVnA5jXeWMEyYhSNktLnpDL2gBUCsdbkov5VjiOX7 CRTkX0UgNWRjyFZwThaZADEvAOo12M5uSBk7h07yJ97gqvBtcx45IsJwfUJE4hy8qZqsA62A nTRflBvp647IXAiCcwWsEgE5AXKwA3aL6dcpVR17JXJ6nwHHnslVi8WesiqzUI9sbO/hXeXw TDSB+YhErbNOxvHqCzZEnGAAFf6ges26fRVyuU119AzO40sjdLV0l6LE7GshddyazWZf0iac nEhX9NKxGnuhMu5SXmo2poIQttJuYAvTVUNwQVEx/0yY5xmiuyqvXa+XT7NKJkOZSiAPlNt6 VffjgOP62S7M9wDShUghN3F7CPOrrRsOHWO/l6I/qJdUMW+MHSFYPfYiFXoLUZyPvNVCYSgs 3oQaFhHapq1f345XBtfG3fOYp1K2wTXd4ThFraTLl8PHxCn4ywARAQABzSRNYXR0aGlldSBC YWVydHMgPG1hdHR0YmVAa2VybmVsLm9yZz7CwZEEEwEIADsCGwMFCwkIBwIGFQoJCAsCBBYC AwECHgECF4AWIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZUDpDAIZAQAKCRD2t4JPQmmgcz33 EACjROM3nj9FGclR5AlyPUbAq/txEX7E0EFQCDtdLPrjBcLAoaYJIQUV8IDCcPjZMJy2ADp7 /zSwYba2rE2C9vRgjXZJNt21mySvKnnkPbNQGkNRl3TZAinO1Ddq3fp2c/GmYaW1NWFSfOmw MvB5CJaN0UK5l0/drnaA6Hxsu62V5UnpvxWgexqDuo0wfpEeP1PEqMNzyiVPvJ8bJxgM8qoC cpXLp1Rq/jq7pbUycY8GeYw2j+FVZJHlhL0w0Zm9CFHThHxRAm1tsIPc+oTorx7haXP+nN0J iqBXVAxLK2KxrHtMygim50xk2QpUotWYfZpRRv8dMygEPIB3f1Vi5JMwP4M47NZNdpqVkHrm jvcNuLfDgf/vqUvuXs2eA2/BkIHcOuAAbsvreX1WX1rTHmx5ud3OhsWQQRVL2rt+0p1DpROI 3Ob8F78W5rKr4HYvjX2Inpy3WahAm7FzUY184OyfPO/2zadKCqg8n01mWA9PXxs84bFEV2mP VzC5j6K8U3RNA6cb9bpE5bzXut6T2gxj6j+7TsgMQFhbyH/tZgpDjWvAiPZHb3sV29t8XaOF BwzqiI2AEkiWMySiHwCCMsIH9WUH7r7vpwROko89Tk+InpEbiphPjd7qAkyJ+tNIEWd1+MlX ZPtOaFLVHhLQ3PLFLkrU3+Yi3tXqpvLE3gO3LM7BTQRV4/npARAA5+u/Sx1n9anIqcgHpA7l 5SUCP1e/qF7n5DK8LiM10gYglgY0XHOBi0S7vHppH8hrtpizx+7t5DBdPJgVtR6SilyK0/mp 9nWHDhc9rwU3KmHYgFFsnX58eEmZxz2qsIY8juFor5r7kpcM5dRR9aB+HjlOOJJgyDxcJTwM 1ey4L/79P72wuXRhMibN14SX6TZzf+/XIOrM6TsULVJEIv1+NdczQbs6pBTpEK/G2apME7vf mjTsZU26Ezn+LDMX16lHTmIJi7Hlh7eifCGGM+g/AlDV6aWKFS+sBbwy+YoS0Zc3Yz8zrdbi Kzn3kbKd+99//mysSVsHaekQYyVvO0KD2KPKBs1S/ImrBb6XecqxGy/y/3HWHdngGEY2v2IP Qox7mAPznyKyXEfG+0rrVseZSEssKmY01IsgwwbmN9ZcqUKYNhjv67WMX7tNwiVbSrGLZoqf Xlgw4aAdnIMQyTW8nE6hH/Iwqay4S2str4HZtWwyWLitk7N+e+vxuK5qto4AxtB7VdimvKUs x6kQO5F3YWcC3vCXCgPwyV8133+fIR2L81R1L1q3swaEuh95vWj6iskxeNWSTyFAVKYYVskG V+OTtB71P1XCnb6AJCW9cKpC25+zxQqD2Zy0dK3u2RuKErajKBa/YWzuSaKAOkneFxG3LJIv Hl7iqPF+JDCjB5sAEQEAAcLBXwQYAQIACQUCVeP56QIbDAAKCRD2t4JPQmmgc5VnD/9YgbCr HR1FbMbm7td54UrYvZV/i7m3dIQNXK2e+Cbv5PXf19ce3XluaE+wA8D+vnIW5mbAAiojt3Mb 6p0WJS3QzbObzHNgAp3zy/L4lXwc6WW5vnpWAzqXFHP8D9PTpqvBALbXqL06smP47JqbyQxj Xf7D2rrPeIqbYmVY9da1KzMOVf3gReazYa89zZSdVkMojfWsbq05zwYU+SCWS3NiyF6QghbW voxbFwX1i/0xRwJiX9NNbRj1huVKQuS4W7rbWA87TrVQPXUAdkyd7FRYICNW+0gddysIwPoa KrLfx3Ba6Rpx0JznbrVOtXlihjl4KV8mtOPjYDY9u+8x412xXnlGl6AC4HLu2F3ECkamY4G6 UxejX+E6vW6Xe4n7H+rEX5UFgPRdYkS1TA/X3nMen9bouxNsvIJv7C6adZmMHqu/2azX7S7I vrxxySzOw9GxjoVTuzWMKWpDGP8n71IFeOot8JuPZtJ8omz+DZel+WCNZMVdVNLPOd5frqOv mpz0VhFAlNTjU1Vy0CnuxX3AM51J8dpdNyG0S8rADh6C8AKCDOfUstpq28/6oTaQv7QZdge0 JY6dglzGKnCi/zsmp2+1w559frz4+IC7j/igvJGX4KDDKUs0mlld8J2u2sBXv7CGxdzQoHaz lzVbFe7fduHbABmYz9cefQpO7wDE/Q== Organization: NGI0 Core In-Reply-To: <20251117100745.1913963-1-edumazet@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Eric, (+cc MPTCP ML) On 17/11/2025 11:07, Eric Dumazet wrote: > mptcp_pm_del_add_timer() can call sk_stop_timer_sync(sk, &entry->add_timer) > while another might have free entry already, as reported by syzbot. > > Add RCU protection to fix this issue. Thank you for the report and even more for the fix! > Also change confusing add_timer variable with stop_timer boolean. Indeed, this name was confusing: 'add_timer' is in fact a (too) short version of "additional address signalling retransmission timer". This new 'stop_timer' boolean makes sense! > syzbot report: (...) > Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout") > Reported-by: syzbot+2a6fbf0f0530375968df@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/netdev/691ad3c3.a70a0220.f6df1.0004.GAE@google.com/ > Signed-off-by: Eric Dumazet > Cc: Geliang Tang The modification looks good to me: Reviewed-by: Matthieu Baerts (NGI0) While at it, just to help me to manage the backports: Cc: stable@vger.kernel.org > v2: Updated/Added Reported-by:/Closes: tags now syzbot report finally reached netdev@ mailing list. Out of curiosity, is it not OK to reply to the patch with the new Reported-by & Closes tags to have them automatically added when applying the patch? (I was going to do that on the v1, then I saw the v2 just when I was going to press 'Send' :) ) I don't mind having a v2, it is just to save you time later, but maybe there is another reason. Cheers, Matt -- Sponsored by the NGI0 Core fund.