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 61BC53E3D95; Thu, 20 Aug 2026 11:06:26 +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=1787223987; cv=none; b=ApwS2eIFN2HK6OS9uYaNqemnRKA6+p4bQaUrRrvWcKP3o+f1+Gaoly4RbQxNENobnV8mX5Te4HzkgcqoWjGr5ZuygFB3eAjT4OJGjNvT7abuIwb8qMMG9Xx790V+/UK+2cUhlZSOXIbiYXWHBlU6sgDNxwoAKobTuYO6jgGze3A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787223987; c=relaxed/simple; bh=f2FdYqKKiYNChib1cHpBpuIV9SFOoggSwnxewz4A31M=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=s5QpBuq5Vt4NHYROtXFeQfHZFQBc9xySFn39723pA8ByHfK8L6c1vqIRpdzl4LgQVbKRctmdF5OeDbk5gZfxpHk4FW4XaBQa9cl4XUT3pVumUNBf2FHVw5w/bPxQ2OANmGNeniIPZ7LSNDdOU/9rEth9sO52cF0b4ecD5a+Isqo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WcwvmnG4; 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="WcwvmnG4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EAF521F00A3A; Thu, 20 Aug 2026 11:06:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787223985; bh=3+6mlSi2lY6fi+GLOAuc57eBU64IlSnWMGCsUDAH6/I=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=WcwvmnG4ccL7UK1rc+3aSQlG+bmCg/OxsJDKA+3cmDrcwyy2pxDdWRblL40Ce6wFe tdeYUqhlSlPLO3xarPjZzeS9tjHdegibV5+My3ySvOC+fWaMPkqUcGeNIl2pFaei2A RVWt7/ZSQlbqm/Kwn2nWSJTg4n0sfh8J+YydxmKI9M0SUx836Mx/YjcjfdLMFjZ7im bJngLHpTNHNJ3gcRcAQz3n2zrnXEXywgNYuwR2e7fY1q85p1wrYkjfnAPrPIaQft2T elveuHJrEpJV1IawQC9WNcMz/NsaHJZ6MzLFky5dzkBIWgYqvyNufFm/f5es04L08V C2tmB+u0k+nGA== Message-ID: <1e62d538-721f-486b-bb91-64864b3c5c8d@kernel.org> Date: Thu, 20 Aug 2026 13:06:22 +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-next v3 5/5] Squash to "mptcp: pm: init and release mptcp_pm_ops" Content-Language: fr To: gang.yan@linux.dev, sashiko-reviews@lists.linux.dev Cc: mptcp@lists.linux.dev References: <20260819125629.49823-1-gang.yan@linux.dev> <20260819125629.49823-6-gang.yan@linux.dev> <20260819131205.3A0201F000E9@smtp.kernel.org> <7b85c6e1e4e270bd368fb7dc6d24279c1c20c3b2@linux.dev> <74e63e9935103e9fab16ea81e0ea7480f9c7d736@linux.dev> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 20/08/2026 12:16, gang.yan@linux.dev wrote: > August 20, 2026 at 5:07 PM, "Matthieu Baerts" wrote: > >> Can you first check if this can happen? I thought that >> mptcp_destroy_common would first close all subflows, remove the token, >> then release everything linked to the PM → so the PM will no longer be >> called at that point for this msk, right? (I didn't check) >> > > Hi Matt, > > Thans for looking at this and kindly remind. > Yes, I just checked the order you described is right, but I thought it > could happen in such order: > > CPU A (softirq) CPU B(disconnect) > ->subflow_token_join_request > ->mptcp_token_get_sock() > ->mptcp_destroy_common() > ->pm_ops_release > ->mptcp_pm_get_local_id(): > msk->pm.ops->get_local_id() <- NULL deref Ah yes, indeed, subflow_token_join_request doesn't hold the msk lock. > WDYT? And, I think the window seems too narrow, we may not see it in practice, > maybe a NULL check is enough? Would it be safe to have a NULL check? Could you have something like this? CPU A CPU B -> if (ops) -> mptcp_destroy_common() -> pm_ops_release() -> msk->pm.ops->get_local_id() The BPF module might have been unloaded. (Again, I didn't check in details, only looking at your reply.) Cheers, Matt -- Sponsored by the NGI0 Core fund.