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 7846945039 for ; Wed, 27 May 2026 04:44:57 +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=1779857098; cv=none; b=giO1Lc3xvYhCoD+H5ZReaxEjR78NMQ+gx0mv7VwOBqHDZQ9ONEXjb1yoyJhjx67x68Olscx5tni1zb7oCuCLxePJ405YZsTMqeZGIl8SJj5FQ6uM84pBSPk/fK4Qvm+yLqODYu9WIxo6BPK6AKtZaF2mNf7jX9eXzF2S77ZvZAw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779857098; c=relaxed/simple; bh=drWlSRiQ//EEWu/U2lCk0ikN6dCSXdA68fI5nR8yYNs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EtISu+qgdu/r2PvcOG8uWBTeSyv6Ca703Q/ZQt0IOGdFLjgJFIE/AA1c/JugakPzdkaNcAj2MNz8JVdhGs57YQvZpGgtgh3or+H6ezN9rIxM+EEQbdZD5WMpCP6Gt/l889keSrX5SqsDGo8q8Yia7XDOIV9O7fwnUNao1SfIpYM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gQfzA1X0; 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="gQfzA1X0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB9851F000E9; Wed, 27 May 2026 04:44:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779857097; bh=bUKcg1v4QWpyjhvqt6/XngwZJbSquPikL7FkJlWMDf4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=gQfzA1X0EBsflqTclg5SvpXR69MqA3M+3BYDipwyBxTpvDGXYlvpNs9hnVPHlgI00 gAkqJWyzyybVZO9zvyjJBXi838xi11af1tCsOQnRlQpzexX7u3ZsJYd92vrBcdHU1R nOMdSAG6IWzYoHhmdXTQDDB9L9KhDXhtSn6jm4o8dVBtDAdF/SLFoIt3GX/hkjwpUC 0ywMbIb8GLU2dmS2Fz8AqSn5zIx6hg/4A/9B1jKPzjUk2GVEe73aTgplMwyRFJnVlG MeYyh/HL+4+Xwv/HAWMpk0/RVhHHQ9PUc7GJkfScjw8N5hNd5nP90hmb6puOtz5bO9 clOSMwQikDXog== Message-ID: Date: Wed, 27 May 2026 14:44:52 +1000 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 2/2] mptcp: use sk_shutdown_timer_sync() for add_addr timer teardown Content-Language: fr To: Li Xiasong , mptcp@lists.linux.dev Cc: lixiasong1@huawei.com References: <20260526103647.732350-1-xiasong.lee@gmail.com> <20260526103647.732350-3-xiasong.lee@gmail.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Li, On 26/05/2026 20:36, Li Xiasong wrote: > From: Li Xiasong > > Sashiko reported a possible use-after-free in add_addr timer teardown. > > The add_addr timer callback can re-arm itself on the sock_owned_by_user() > path. In final teardown paths, sk_stop_timer_sync() only waits for a > running callback to finish, but does not prevent a concurrent callback > from re-arming the timer. > > Use sk_shutdown_timer_sync() for add_addr timer teardown so the timer > cannot be re-armed after teardown starts, preventing a possible > use-after-free on a freed add entry. Sashiko is saying that if sk_reset_timer() is called after sk_shutdown_timer_sync(), it will not re-arm the timer, but in this case, mod_timer() will also return 0, and the socket refcount will be incremented. https://sashiko.dev/#/patchset/20260526103647.732350-1-xiasong.lee%40gmail.com It is not clear to me how to solve that without checking whether timer->function is set or not after having called mod_timer(), because that seems quite hackish... Cheers, Matt -- Sponsored by the NGI0 Core fund.