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 0BB102F7AD6; Thu, 13 Nov 2025 17:35:37 +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=1763055337; cv=none; b=jb5tOAflzzmBPj+xr/JDxo9Ahu8RLRXFE7vRfkAy4dl+AOp0jKnObTsLzvazX8rmoHGv7/iVmP3Il2LHVxPH84aJbtBx6Z3dUoK7tAHTzPbtMv/jRFKYePuIW6QSGpxOThTsgvey0SEobyTksVYZ0iRJVA94B8wXXfR5KpLoDN8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763055337; c=relaxed/simple; bh=pnjB2/QfMS1wcR08UjEVufjezdYxJWJrOY8l7Kog+ss=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kuLaBLKYtKfRFe41+5YrOYedqOHA34O7yv5z6oAOTLb95siekXnjIQRwPQwzw3sffN7JeK2UCG/FJTrzDXRI++QlcwEjcZeH709pB1NfABGwdkypbIVLh9uJG3Z6qlv7SqX8MDx1YuPtP/DpE8mLffv+lg7vujfbSs+tAKlEvF8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HPuzll1n; 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="HPuzll1n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90E1EC4CEF7; Thu, 13 Nov 2025 17:35:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763055336; bh=pnjB2/QfMS1wcR08UjEVufjezdYxJWJrOY8l7Kog+ss=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=HPuzll1ny74wtDBA9k+bSGe4zPhMemmefnHO4RUikv7eIlkgMeNruTn6nyDCVLBAv 4hojWmLNjqnimhz6ztfCcinSq4BO4zmrPg0WiaGV2IYhHZgd+027Po/0D75HVDs/Sk 8j/MOAxU2UFHRufgvziwoG2M6KkRcGEzM5j0YScqs/IUlD8+5dJ2ec1jLLGhlu3oXl lp8J746xj2tEspszqu7SPuRb+EMSb8PlkIu3zUa2853okYe4OUiuq1eNYMQvOPUsfV YJtmdx+fC7aR9Ky8vnlI/0wa4p82uQjfIRPvXOFrmFpPAx3tyw9WGapeyruRPQ/JkK sguVGnDlYHCMg== Message-ID: <2a8efd6f-34d5-480f-8ca1-efef2959fffd@kernel.org> Date: Thu, 13 Nov 2025 18:35:31 +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 net] mptcp: fix race condition in mptcp_schedule_work() 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+355158e7e301548a1424@syzkaller.appspotmail.com, "David S . Miller" , Jakub Kicinski , Paolo Abeni , MPTCP Linux References: <20251113103924.3737425-1-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: <20251113103924.3737425-1-edumazet@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Eric, (+cc MPTCP ML) On 13/11/2025 11:39, Eric Dumazet wrote: > syzbot reported use-after-free in mptcp_schedule_work() [1] > > Issue here is that mptcp_schedule_work() schedules a work, > then gets a refcount on sk->sk_refcnt if the work was scheduled. > This refcount will be released by mptcp_worker(). > > [A] if (schedule_work(...)) { > [B] sock_hold(sk); > return true; > } > > Problem is that mptcp_worker() can run immediately and complete before [B] > > We need instead : > > sock_hold(sk); > if (schedule_work(...)) > return true; > sock_put(sk); Thank you for having released the syzbot issue with the fix! That's way easier for us when the fix is provided with the bug report! :-D The modifications look good to me: Reviewed-by: Matthieu Baerts (NGI0) This patch can be applied to -net directly, ideally with: Cc: stable@vger.kernel.org (Just for me to be able to track issues with the backports. If it cannot be added, I can also track it "manually" if preferred.) Cheers, Matt -- Sponsored by the NGI0 Core fund.