From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 1EA7D3E49EF for ; Tue, 21 Jul 2026 17:44:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784655852; cv=none; b=RR6SaEj19vJk0BgyryDZbL8916D4gXXngCWv6DfHKeyqOXb7lBwMa2KYdiD8HjKk6d3OIRPmWxhaDyvosUPxHS8RGwpYC3ejkM52vVhtiT9n8Pe9JwUcFpj/D/Db2MEYhtGE8ZwevVdpXDA7Vrsw9eCKsVE1Y8gS2pOvtnpyLww= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784655852; c=relaxed/simple; bh=riOloDyTxY/85C2hiT1xoqmuVNoe/5TBFzrh3ZPg/yQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=j/eaQN/s3K73qkINe7KeyvgJVA0kLQnclIyH0tU/bQKG716tCz+K9LpykgQZk9eerimhXQB0fq8w+xSuSIAwiyxa/RRedX8p2SgRoUGS6m/YepmGUjeAGd5RLAQMMLAYYn1DHfW2Dr7fQuSc/EQ+EqkvqDVcSNz7asKA6LG4mdg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Qyu9aRiv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Qyu9aRiv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BB29C1F000E9; Tue, 21 Jul 2026 17:44:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784655850; bh=3WxDFGPiu2T4+UAaYYGx9wlBUqX7mKevZJcsgyszGE0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Qyu9aRiv1IVGgA9Q7MKsrNLIf3lSJGgscq2q/qhz8Lbo0HXTPLySxsUuIZtddtnVq n4atV/sP9fK+3X4DBi1dc4dvD5BaJe2X3WsIceOrm3qhNP6/N63staw4BqjWp5EGSV hvDdLwD57IEw6nj9otuoLVsHYnrnRMa3EuaTIlZAS4zkdoE8wCyOEfvPLvipBYPWfh dBnpWNcvhEhm9PN31wa8f6yycMF6UBL/NKwKQyS1HHKzYayB8PCR34qzcztmmPh9g1 nK3LcTBqo1uT1FCHyruEoQrN6naJFIVdfL876O0dT+w/C1QE0Qx6/2mQQZ2tXGQ9+g wXQdJkFqsp3jQ== Message-ID: Date: Tue, 21 Jul 2026 19:44:07 +0200 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH mptcp-net] mptcp: pm: userspace: fix use-after-free in get_local_id Content-Language: fr To: Geliang Tang , mptcp@lists.linux.dev, Xuanqiang Luo Cc: Geliang Tang , GangYan References: <4e50adfde3b80f433e13b86919596be229045edc.1782799876.git.tanggeliang@kylinos.cn> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Geliang, On 30/06/2026 08:11, Geliang Tang wrote: > From: Geliang Tang > > In mptcp_pm_userspace_get_local_id(), the address entry is looked up under > spinlock, but its id is read after dropping the lock. A concurrent deletion > can free the entry between the unlock and the read, leading to UAF. > > Fix by copying the id into a local variable while still holding the lock, > and use -1 as a "not found" sentinel. Thank you for the fix, it looks good to me! Reviewed-by: Matthieu Baerts (NGI0) I hope that's OK, but I added Xuanqiang Luo's Tested-by tag, as he sent almost the same patch recently (BTW, thank you Gang for spotting that): https://lore.kernel.org/20260713074722.47921-1-xuanqiang.luo@linux.dev While at it, I also added the KASAN report in the commit message, that's helpful to prove this issue can happen and was tested. New patches for t/upstream-net and t/upstream: - 6b5c6ac1e2fe: mptcp: pm: userspace: fix use-after-free in get_local_id - Results: 08c6392dbaf1..fef06e990c6c (export-net) - Results: ea196b8ada26..f984839d1257 (export) Tests are now in progress: - export-net: https://github.com/multipath-tcp/mptcp_net-next/commit/05643696039e56609f35092206657c6cdb725baf/checks - export: https://github.com/multipath-tcp/mptcp_net-next/commit/97ce11d2793f114ca652a565a8d2795c085d8ff1/checks Cheers, Matt -- Sponsored by the NGI0 Core fund.