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 3378F36A37A; Thu, 20 Aug 2026 15:00:35 +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=1787238036; cv=none; b=HWEZHztyPvmq8IcxPc37S5QomOZKIYnZTwZSvhnJbbkZXsdk5ChGZc1orbRJo/Z/wx2dsKB3xLO79RUjawJiyVbJOQ6SSDQDqfyVGiob8Acw0uW6xhbxTKyc3sLcJR7Xj4HlSPrVkth7No2TsqwbGWwscWSjwBol1EHuB0/t+48= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787238036; c=relaxed/simple; bh=soaUoffn+XrvpyAoSbeleOhKWGBBcLStmcjISqF00Js=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=G39GTb9YGMgUv24AqmAlMMHlYdDnlmBI9TJKVvzcjz0UftNOv2TFqsgsxPCNubhaJpnU5IB8GDmDQ4ELJrhHIhsM5poubDHE0Hss4FORixMlRIgII8VSL7db5JNRs3oDAelnqMgCAvR0n5Wq18XnUB5n/TxwzHiVi0aKGla7izg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=waB7wnXK; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="waB7wnXK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D7BF1F000E9; Thu, 20 Aug 2026 15:00:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787238035; bh=N/hV6xJNWANWdV1E9a0UQffaIxaq2dMOxq0HeTjXFxA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=waB7wnXKaNX/dMB8jQu6QbTHv/hWKsrNQ4zZVtv4iQa0Urv4Ws3rSeVlu0SCgq/gl Pvr+vjA/Hn1N9MvaqcMXjEYz5fdh0kSHBXhoDx3UbUsd9p9p5YHms3PhMFiu6G1WAR GtixrbfjHSKsLkMigiI3DT+3vNeqpPGpbDAT3nEo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Qing Luo , "Matthieu Baerts (NGI0)" , Jakub Kicinski Subject: [PATCH 7.1 011/228] mptcp: pm: fix data race in add_addr timer callback Date: Thu, 20 Aug 2026 16:52:33 +0200 Message-ID: <20260820145244.806305398@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145244.450574346@linuxfoundation.org> References: <20260820145244.450574346@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Qing Luo commit a7aad5b69d3bdaec20a3ed9284e184502450c0cd upstream. The timer callback reads entry->retrans_times outside pm.lock to decide whether to call mptcp_pm_subflow_established(). Since mptcp_pm_announced_del_timer() can concurrently set retrans_times = ADD_ADDR_RETRANS_MAX under pm.lock, a race condition exists. I discovered this issue while studying the code. AI tools helped me to verify the issue can potentially happen under race conditions. Use a local 'retransmit' flag set inside pm.lock to capture whether retransmission is still possible when the lock is taken. This allows to call mptcp_pm_subflow_established() accordingly, and not depending on the situation that can be different when checked outside the pm.lock. Fixes: 348d5c1dec60 ("mptcp: move to next addr when timeout") Cc: stable@vger.kernel.org Signed-off-by: Qing Luo Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260803-net-mptcp-misc-fixes-7-2-rc6-v2-4-b8f496d71664@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/mptcp/pm.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/net/mptcp/pm.c +++ b/net/mptcp/pm.c @@ -345,6 +345,7 @@ static void mptcp_pm_add_timer(struct ti struct mptcp_sock *msk = entry->sock; struct sock *sk = (struct sock *)msk; unsigned int timeout = 0; + bool retransmit; pr_debug("msk=%p\n", msk); @@ -377,14 +378,15 @@ static void mptcp_pm_add_timer(struct ti entry->retrans_times++; } - if (entry->retrans_times < ADD_ADDR_RETRANS_MAX) + retransmit = entry->retrans_times < ADD_ADDR_RETRANS_MAX; + if (retransmit) timeout <<= entry->retrans_times; else timeout = 0; spin_unlock_bh(&msk->pm.lock); - if (entry->retrans_times == ADD_ADDR_RETRANS_MAX) + if (!retransmit) mptcp_pm_subflow_established(msk); out: