From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pz2-f12.google.com (mail-pz2-f12.google.com [74.125.228.12]) (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 448D33EB7F4 for ; Tue, 22 Sep 2026 05:43:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.228.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790055785; cv=none; b=WnSjP9uu+UXmIPr6+uQdhTXjiTvKHT3X3AINcQ9HrCWXmG9+ATxGNbOwArq2IJoL+i9ToECfZUTTNLht2x7Iq3WLaGGCavksc4brXAt/JSUWJer6pIwwEjw5LSX4fBnlfVnNWro8ZH/0q/NulWBAHD+Vz2+Try6Ctz8McyqEa3c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790055785; c=relaxed/simple; bh=qaR7d/zM90YPWHcOm3TYV77R2th6xdwLV93lEheSkeY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=uQ5pxOUNQ1HsjIaRkineb9+XNEaGdqsia4gG1klj/VybKrn0RsUP5JfLP4x/3430VC9wXEzK1KioKeBEr029KepkC93oMuDZ1fGB/XawkRc28FK3qkdHVoESPT4TEgcmUJryiaNrZpwJX9ENhNQ94l3+MAW26GCuVbjnda4O1Us= 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=Ie8Cb0ip; arc=none smtp.client-ip=74.125.228.12 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="Ie8Cb0ip" Received: by mail-pz2-f12.google.com with SMTP id 41be03b00d2f7-cc1cea4c79fso1602495a12.0 for ; Mon, 21 Sep 2026 22:43:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790055778; x=1790660578; 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:content-type; bh=ss6yyG18xKmL3ChDu352XFK2c5fShKuGkPx5v64MPyE=; b=Ie8Cb0ipIlW8LQAyMJbvlxNypO48a+OIbWvEEkf2WdnZBuDaGyECiL3u5+4TcReJBx dD6YS3eAV/KQrqStDLASXBrbTxavOWlYf4Skkky9x2eYjmihfsXzGuQ78yQPrpC/mjL5 wGPUTUJgWHG3plmCEs5PWNVjCqa+C2EkcJRvTvUQ/sS9gGxkkTxatVOLYkbi2FtMX4Ul suL0fGq0aMVOWWwjvckYR6qEvqTua7Ook8HxO1E50ajJMdr5oI8wKnJ6luyvev6F3XAx iUmfA0ahdydFxSV7yZuxktdePP0k3MVgJZedAhFnXIk/S8ade2Cg91IbnRuhymHVvmnt +JQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790055778; x=1790660578; 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:content-type; bh=ss6yyG18xKmL3ChDu352XFK2c5fShKuGkPx5v64MPyE=; b=LcrKV8bQ1T/s7QUu7FISdv06VAcu0WfZdnFTyw9d9xZ0X1I05UAFx2K0FwutKYAUqb DhnrKM9TdoKW7P33Xhs9rutKLihP9ab4MKtJ8iv9fzqCFfMj2w2KYNvgVCCt4xFEGOcy Wnl4XloWGRo4YITYE/8wbCMiQR+vhbJrnMGF4O+STGOJ1RoH8c6XvlDzkVqLKvPNtOYV ArgpvOWxnaJ/hTClZxANhfKFrSLQOcBr7zxt0sYrBgqo8OXG1B8bMDt539Wjg3JuygWM 9vuF8T4igCfWDt4bInFJxpzYSnumUMKbULPzd26gXTcNDcExaXJlwzK+BEMhORT6lSa7 x6pA== X-Gm-Message-State: AFuF++l11m2HY8Siil5PMQKQCCSeSXiXfR39ZI815a/0CND7WzymUXh/ vRyWU4rUoWgp1qSwv3j2g/zR6vYLk6wrleNO3IGGg5Lxl94U3j/OsZd0 X-Gm-Gg: AYBFou0fo47IH1S/RItCdeKN76cuwPHu+hoir/7rCMraNdfXghNNWM5GOc5zNFe4XYG NdfmiXAZhx6/fPjmRA8F5kwh2Ah06BxDdSQ9skj4k76qly3oJfOm+crysKg6Qn2/t/giZmPKvBG Xi71yeHT/jIKTTQUdH6nDvgjJuddP8DH0rZb0CTfZ5uxzrPdG78SCYuzRwhMgjcC9IyCeD8VGWN ZiRX4nNJ67PepoeZag3AK+czQ13CjfjuxOUNe6pb4iqsJrGCe3EhyBWJLRicI3F/UcRmXHTEdc6 RfkylNFdF4sbVAmCgkYvlz1jJZGFoVjjhndT70mM81+tuZn1VYAonXxpk6wJirQSGxZYvNrwJu2 Kd4cITZwkToUSN14yGimUMdm2bgO/X8XhgqO/jI5h/5lyIcBwD1Jx3v3dgoMxkZxDsesZIrmDdq Sm3qMgkFGR4ISf8qY9/92dfGc3I5v63pVJM1EJs8UOQShM/ytyUj0/GakqG7WlzDwrZQFhzUIX3 J6GwhN/84NWxl27N/apX4YRhmRso+lB X-Received: by 2002:a05:6a21:9185:b0:3dd:d91d:e2c2 with SMTP id adf61e73a8af0-3ddec7c94fbmr77047637.48.1790055778001; Mon, 21 Sep 2026 22:42:58 -0700 (PDT) Received: from localhost.localdomain ([202.189.109.160]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cc756a317d7sm295136a12.16.2026.09.21.22.42.55 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 21 Sep 2026 22:42:57 -0700 (PDT) From: Ginger Li To: johannes@sipsolutions.net Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] wifi: mac80211: Fix a race when expiring a mesh path Date: Tue, 22 Sep 2026 13:42:53 +0800 Message-ID: <20260922054253.11976-1-ginger.jzllee@gmail.com> X-Mailer: git-send-email 2.46.0 Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit My static analyzer identified a potential issue in 'net/mac80211/mesh_pathtbl.c': mpath_expired() reads mpath->flags and mpath->exp_time without holding mpath->state_lock, while mesh_path_fix_nexthop() and the other writers update both fields under that lock. In mpath_lookup() and __mesh_path_lookup_by_idx() the unlocked check is followed by taking the lock and clearing MESH_PATH_ACTIVE, so the check and the update are not atomic: CPU0 (mpath_lookup) CPU1 (mesh_path_fix_nexthop) mpath_expired() reads the stale flags/exp_time and returns true spin_lock_bh(&mpath->state_lock) mpath->exp_time = 0; mpath->flags = FIXED|SN_VALID; mesh_path_activate(mpath); spin_unlock_bh(&mpath->state_lock) spin_lock_bh(&mpath->state_lock) mpath->flags &= ~MESH_PATH_ACTIVE; spin_unlock_bh(&mpath->state_lock) A path which mesh_path_fix_nexthop() has just set up as MESH_PATH_FIXED and MESH_PATH_ACTIVE then has MESH_PATH_ACTIVE cleared again, and forwarding to that destination silently stops. Take mpath->state_lock before evaluating mpath_expired() so that the check and the clearing of MESH_PATH_ACTIVE are atomic with respect to the writers. Fixes: 60854fd94573 ("mac80211: mesh: convert path table to rhashtable") Signed-off-by: Ginger Li --- net/mac80211/mesh_pathtbl.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/net/mac80211/mesh_pathtbl.c b/net/mac80211/mesh_pathtbl.c --- a/net/mac80211/mesh_pathtbl.c +++ b/net/mac80211/mesh_pathtbl.c @@ -247,9 +247,10 @@ static struct mesh_path *mpath_lookup(struct mesh_tabl mpath = rhashtable_lookup(&tbl->rhead, dst, mesh_rht_params); - if (mpath && mpath_expired(mpath)) { + if (mpath) { spin_lock_bh(&mpath->state_lock); - mpath->flags &= ~MESH_PATH_ACTIVE; + if (mpath_expired(mpath)) + mpath->flags &= ~MESH_PATH_ACTIVE; spin_unlock_bh(&mpath->state_lock); } return mpath; @@ -290,11 +291,11 @@ __mesh_path_lookup_by_idx(struct mesh_table *tbl, int if (!mpath) return NULL; - if (mpath_expired(mpath)) { - spin_lock_bh(&mpath->state_lock); + spin_lock_bh(&mpath->state_lock); + if (mpath_expired(mpath)) mpath->flags &= ~MESH_PATH_ACTIVE; - spin_unlock_bh(&mpath->state_lock); - } + spin_unlock_bh(&mpath->state_lock); + return mpath; } -- 2.43.0