From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f180.google.com (mail-pg1-f180.google.com [209.85.215.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 44EC7366069 for ; Fri, 6 Mar 2026 03:14:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772766851; cv=none; b=FRC+t9uWKq6unF6xr5C7jiKmnNNLens9QGIiMRF5rqTz2+jNRnFWI0U+rAlxc3oQi6Nfqc/piRaswHg9RbP6mxQ9/wdZxxfTSL4jWk2BPHxmlM4aJaeO6mhoGJ172WogFIcRfRCb7IpZEVamoFDw4Za1i/aKlLtBio/N2oV4bZ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772766851; c=relaxed/simple; bh=ckTCUOoiVNYeEw/M1IXNtDeSz8draygJacRfDD11QLw=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=pi6aldHOMuHScI77/XgD783yU638OWrGX/GD9CwhOGR/Jmyq2Lg5Cu7R8zg/DBcrF6ktTVhK2i4wTFn4fFuL5g3ol0nhUWX7ojnuzU5ARtRv+vcE6sanfz+byiIZjNG4om71pT97VHq71zusJ/kD18r2j5INCqEVVXEviGMhQjI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=L+iQM0m1; arc=none smtp.client-ip=209.85.215.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="L+iQM0m1" Received: by mail-pg1-f180.google.com with SMTP id 41be03b00d2f7-c70d802cc05so769390a12.3 for ; Thu, 05 Mar 2026 19:14:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1772766850; x=1773371650; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=GAKk9BLlPBGd+3xOdk2XRyvunkKExwApsKu0QsVvEfo=; b=L+iQM0m1bH7knQFT+BgbZ431B64R2E99qTPmefwUADWKexlN2vSd6NBSzS0p3lA2vN 72cHxND6nHIEMwxhcN0nmZ84jpv4+4DLA/3wvA19VSwRCdNZ4E6sGc7ID/bZQUua71gQ 18DhBJ5KRd860pT5uxVJ7e7YBo7Jok2FZFbbOoraxqD5JWzPRif1BnwJc/tH99Elb/Ew gKpcM+vCb5d0ii8/6HQDkt8J/CvTs0cQWu4CLha1J0AbHvuq9d3tD+7sAS0uykfRiurR t2htM4aNEg4qU39TtG8KLdSKSes5mgKv9NU95iPyuyyul7ANJCGpzWA+TuQ2VA82Vygi Zt8Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772766850; x=1773371650; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=GAKk9BLlPBGd+3xOdk2XRyvunkKExwApsKu0QsVvEfo=; b=sH7TmiaEu7dOeLgEjrKqnAwLZpkC6xOE2pT3lnW+v72IjqdvZBz5aZucwDoikgQmmK I2jjR1c+UJlGn/0treSIKf6Zs8HxmfOOFtogRVvBFRIp/o4Z7qnM4wXLaSA3YLVkRmnD J0nslTf7FfPHz6h1WpF4tUU2eL7GcSaqWS5UOWHjpFA8e+5Um+7MnMdi3PgC1fPZphyg U3w6Nsrrfz7iHVGmYT5S+udFAP51A6mrckZ9HgRzpmgEW/JyrwKhkfu9XAnpqlzVVhvK XVuPhvdLssejIblYqLksP3x6thuY8hMoKC0RzlH3d3cdR57rYdg1PCJU4/yHpFve8pZb am1w== X-Forwarded-Encrypted: i=1; AJvYcCXq0nxXrQoik/78XZPw1FnUEZX21QgUNWDHKo/dRLt39lQ8GqbBwNZ0zVF4F1nP+wE+JnFpEV4=@vger.kernel.org X-Gm-Message-State: AOJu0YymkhdXpaoUFhpf+5KJkG5IfmlQtSrgXdGYPYpfZiGgxKSVa5jo gt0q8aUO0R7Ocnuq7sSN94TF2KX83dhCUJ6mm3GEvOafwXAc3iNfj2FD X-Gm-Gg: ATEYQzzWLzeNmIYbDsJZkxpyc+lf1Y+Omz2Gh8vHLZW2k6M+82M2mdIB9eFCghdExz6 A0WEa4umxaI0JtLYhqeXdFKieh9sFigyWhfjlhKyghrfUb7ButoiKvU0EQ3Qj9xc/R/NJrAbUFc Dtu+0ItYWo+lIN3FirmCZtyoLS6RZQc82qsQFZWl1/yLwM+73IjIxCmIat2FR7pcZr2lSbrX0rN TmFoixWHYPbcbjWpwocYLIZL3jdKC3o40aE/rxcjPoVmK39ZeYd+50PXLcG6RD7a/DD66xOAdOx gF3pDSlXk5wvGnQDCaWoLKl1ztlzgo4vdo+d+p0c8ZAH8Es4JMpAYEyzwDfLGGybbsw3vvBOz95 lggY6p7iXSUNCo4rua5Jm8kWAzYjq6XTCitT5k1nqjUFyRhjvRKD8EYBq9NrpXZh9mHi+TZF1+W vs9DaL199JbYj7ql4uWTNeBx9WjqbrzjLIzYGWkB4lbFeLV51+mjN3jGIQAT1Nsmb2Q5/hzvw= X-Received: by 2002:a05:6a00:8d4:b0:821:8145:6948 with SMTP id d2e1a72fcca58-829a2f90d65mr429767b3a.7.1772766849425; Thu, 05 Mar 2026 19:14:09 -0800 (PST) Received: from 3ce1e5d2d1b2.cse.ust.hk (191host009.mobilenet.cse.ust.hk. [143.89.191.9]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-829a465b6c7sm144405b3a.25.2026.03.05.19.14.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Mar 2026 19:14:08 -0800 (PST) From: Chengfeng Ye To: jk@codeconstruct.com.au, matt@codeconstruct.com.au, netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, linux-kernel@vger.kernel.org, Chengfeng Ye Subject: [PATCH v3] mctp: route: hold key->lock in mctp_flow_prepare_output() Date: Fri, 6 Mar 2026 03:14:02 +0000 Message-Id: <20260306031402.857224-1-dg573847474@gmail.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit mctp_flow_prepare_output() checks key->dev and may call mctp_dev_set_key(), but it does not hold key->lock while doing so. mctp_dev_set_key() and mctp_dev_release_key() are annotated with __must_hold(&key->lock), so key->dev access is intended to be serialized by key->lock. The mctp_sendmsg() transmit path reaches mctp_flow_prepare_output() via mctp_local_output() -> mctp_dst_output() without holding key->lock, so the check-and-set sequence is racy. Example interleaving: CPU0 CPU1 ---- ---- mctp_flow_prepare_output(key, devA) if (!key->dev) // sees NULL mctp_flow_prepare_output( key, devB) if (!key->dev) // still NULL mctp_dev_set_key(devB, key) mctp_dev_hold(devB) key->dev = devB mctp_dev_set_key(devA, key) mctp_dev_hold(devA) key->dev = devA // overwrites devB Now both devA and devB references were acquired, but only the final key->dev value is tracked for release. One reference can be lost, causing a resource leak as mctp_dev_release_key() would only decrease the reference on one dev. Fix by taking key->lock around the key->dev check and mctp_dev_set_key() call. Fixes: 67737c457281 ("mctp: Pass flow data & flow release events to drivers") Signed-off-by: Chengfeng Ye --- v2: Add fix tag v3: Shift mctp_dev_set_key() to else block and invert the branch logic --- net/mctp/route.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/net/mctp/route.c b/net/mctp/route.c index 0381377ab760..59ad60b88563 100644 --- a/net/mctp/route.c +++ b/net/mctp/route.c @@ -359,6 +359,7 @@ static void mctp_flow_prepare_output(struct sk_buff *skb, struct mctp_dev *dev) { struct mctp_sk_key *key; struct mctp_flow *flow; + unsigned long flags; flow = skb_ext_find(skb, SKB_EXT_MCTP); if (!flow) @@ -366,12 +367,14 @@ static void mctp_flow_prepare_output(struct sk_buff *skb, struct mctp_dev *dev) key = flow->key; - if (key->dev) { + spin_lock_irqsave(&key->lock, flags); + + if (!key->dev) + mctp_dev_set_key(dev, key); + else WARN_ON(key->dev != dev); - return; - } - mctp_dev_set_key(dev, key); + spin_unlock_irqrestore(&key->lock, flags); } #else static void mctp_skb_set_flow(struct sk_buff *skb, struct mctp_sk_key *key) {} -- 2.25.1