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 EA48A33F5B8; Thu, 2 Jul 2026 16:36:01 +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=1783010163; cv=none; b=u4yz8wpZ1hqChP7CVWfATre8RmmR3Gxo69QiBAF9/JDfq00DJQsK4QbdeosWFiTDObhDZAtYUKik5eo6gGXmbBUaaTWoFh4jB2h+aBZ7PNGiStbKHKvqJyf9Vt4qq/7pk12k6if5NzuEMvRPgniFmeI9q4D1ZO8zSfOh7efXAMY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783010163; c=relaxed/simple; bh=Q1+CXadbRm+eQd1HuS7imxNtfBRZ0ZjocNxkZgXSpqw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=d1o/eVGFZYI7ImHxy3IXKcwCQQnR3yZBhrpYkl8T803r35F1sOvw4AgKLROxJavTQOD7odTaD3EII0A6kEKeHJfpsvD6INdmlylDxVVBbnYp8aCGwywPeYjPCgEZzdL4jNngVNsc1agLXZxFofMMlHiNtv8mLwQ86SJcIU6ezks= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=USbCk82c; 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="USbCk82c" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B5AE1F000E9; Thu, 2 Jul 2026 16:36:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783010161; bh=RxRKQyKC+LwS4W3rVnNZtYxyW9RTbG/BAOFjCAtbkl8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=USbCk82cihnnoywJvDkPC5XRL9sx5KZIzNKOfPVPWM+alGVTaufG7WHUmAde4bG3K OWT/BnESMJZgLIWhlWI8HuNGoLUFOKznO2kOm/4e+bfo7RUvmAUbNcFRfUM6uz6Z6P ofQY9v0wFiSkd4gR5ZeCLJD1bRyUJl5MG9s3RFtI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tao Cui , "Matthieu Baerts (NGI0)" , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1 112/129] mptcp: pm: fix extra_subflows underflow on userspace PM subflow creation Date: Thu, 2 Jul 2026 18:20:31 +0200 Message-ID: <20260702155114.460759364@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155112.163984240@linuxfoundation.org> References: <20260702155112.163984240@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tao Cui [ Upstream commit 14e9fea30b68fc75b2b3d97396a7e6adb544bd2a ] The userspace PM increments extra_subflows after __mptcp_subflow_connect() succeeds, but __mptcp_subflow_connect() calls mptcp_pm_close_subflow() on failure to roll back the pre-increment done by the kernel PM's fill_*() helpers. Because the userspace PM hasn't incremented yet at that point, this decrement is spurious and causes extra_subflows to underflow. Fix it by aligning the userspace PM with the kernel PM: increment extra_subflows before calling __mptcp_subflow_connect(), so the existing error path in subflow.c correctly rolls it back on failure. Also simplify the error handling by taking pm.lock only when needed for cleanup. Fixes: 77e4b94a3de6 ("mptcp: update userspace pm infos") Cc: stable@vger.kernel.org Signed-off-by: Tao Cui Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260602-net-mptcp-misc-fixes-7-1-rc7-v2-5-856831229976@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/mptcp/pm_userspace.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/net/mptcp/pm_userspace.c +++ b/net/mptcp/pm_userspace.c @@ -410,18 +410,21 @@ int mptcp_nl_cmd_sf_create(struct sk_buf goto create_err; } + spin_lock_bh(&msk->pm.lock); + msk->pm.subflows++; + spin_unlock_bh(&msk->pm.lock); + lock_sock(sk); err = __mptcp_subflow_connect(sk, &addr_l, &addr_r); release_sock(sk); - spin_lock_bh(&msk->pm.lock); - if (err) + if (err) { + spin_lock_bh(&msk->pm.lock); mptcp_userspace_pm_delete_local_addr(msk, &local); - else - msk->pm.subflows++; - spin_unlock_bh(&msk->pm.lock); + spin_unlock_bh(&msk->pm.lock); + } create_err: sock_put((struct sock *)msk);