From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj2-f10.google.com (mail-pj2-f10.google.com [74.125.227.138]) (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 D63944D7D3B for ; Thu, 8 Oct 2026 15:44:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.227.138 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791474250; cv=none; b=ARlqsRVMI8e3mThOH7yTEgxB4VxlGQdTptXuPYr+rQBMmB6Q4aZWYG44xGZKVFsKzo9Tf4gbKs4Q/uKEa3fH/bFuzrT/ybklLzi2IEc8AYlCAwxTDk9kYCwpd0VYtdpiJF33FNNcegPK4FswR2lTBXhEjZgF8QuJPA6BnzwLylY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791474250; c=relaxed/simple; bh=Q6PFR6LWngt7oO1hw+7z9E0HVKsg7+Hw7FqbuBdwgOE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BFeWHNM885hIR/iOiqCbHAXHq2uKmc+rwKXK7z6RaJ39IH1BRTJ+d+KFFTrz70d1KQ7VlJBY+7i0bpayNIw/zLT4DqrR8owuMtq4il6SZdv9WKsT1dZwbYzoPIBn5c1sgwNIQUerzAKYm6NV5KVthGddtpznx8zhGvlt4QR+aaA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=foxmail.com; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=74.125.227.138 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=foxmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pj2-f10.google.com with SMTP id d9443c01a7336-2dd9bce707bso18263205ad.1 for ; Thu, 08 Oct 2026 08:44:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791474248; x=1792079048; h=content-transfer-encoding:mime-version:references:in-reply-to :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=6SvLzTjNzSdiMNylsVe/w8AxhahIiHxW+GTteqlNxbM=; b=fkk6pH8z/8bhc4dCImMEOWeKmnagvT3DpqmJMplq5a+ZGTWZwDrePgE3hQtcEEj+1F thTaLPWoTYDudBVP6o1qKv3c5v0t0nvqdi4af5ECCOG+iWtN1nsQjEKa9o9DSAXddEqf ryVUBTXlBmnITzT38P8eGfTIYK9Bj2NM/UpDnuR6ZAyY75PDX7qudTRD+6kc8hfcGvFl k8P9NeU168xtQChc8cAM5VqfDz0gsKd4DOl8RLG5rXR/vpBqXeI0L6yRy/I1HZBDkANP ZutC4wWr2lDT2ZTs0UmmuDYo4XcuR6CrpGL5HTkpRQOP5azjX2r9qDVkq5hMK6852E4Z Hnrg== X-Forwarded-Encrypted: i=1; AKwUvBzN0IjPRWViWyPxPDqe2vFdYrC6NMet5kJOl/dvx8Q/GA55tMrn9nDbXdbhCqf6DBNqyBVI/4O9yQ+GiMM3oA==@lists.linux.dev X-Gm-Message-State: AFq9FYL0YgpksfaKLVHGknOiam0W/1k+1v0ZtL6pXBco9UXx24DPNIZB hA7zHelcbGq5Xh8eVYx8RfzI+qRKcmOhGwtyEIpkaBY7tnFOxqTVizDN X-Gm-Gg: AYBFou3ZXdwMLkPe/lx6/g+A3sSZ1cj6rcRJiGc9zrqahZJmVF5p9SnhCSl0s6UlqF8 Fydy7ruHNFcnl4QGD0F9iq5pdaK3CPuSK28vjt70ecFJkx8aHDUemfgxUOMlnFkeEluGoPIxrYT m6Kln5hYS2VCoa5n1CVlGUhzGck2fSkYgM/UYCl3a6JP9b9MokGSzxKeS6d0RFXD9rVFoALVbZB SPeA7DZeCCl/ksF5gYFSoR7UcmWbhPSWF7i9w/lb7vhmoPpFfMdi9NStHVqyekgsAlbGUJ9ZOw+ EycuDv6kv36AunjJtuYsYltOrs4LzQ2fbBZCNMKK/U6e/8q3r1qWOi3/eGBVV7j5MdCmch7y8M4 xhRG08cz8r5XgYvaW2/XlftgVVNgZuGM3MjNHarNFIpuqXWTNINBT2jkxkAWTpYpAyiGGFJzyKN 6hnpyEh6efzcypnq54ZASO8JRmyakW/OxZu8UKRBwpAv996tc1/66Q3ptbyt9CPnnj5Bo3HLq/7 w== X-Received: by 2002:a17:903:380b:b0:2e2:b00f:564f with SMTP id d9443c01a7336-2e600388f4dmr49211465ad.18.1791474247996; Thu, 08 Oct 2026 08:44:07 -0700 (PDT) Received: from foxmail.com ([138.199.21.232]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2e604852563sm27443785ad.62.2026.10.08.08.43.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Oct 2026 08:44:07 -0700 (PDT) From: Jianlin Shi To: kuba@kernel.org, netdev@vger.kernel.org, virtualization@lists.linux.dev Cc: mst@redhat.com, jasowangio@gmail.com, eperezma@redhat.com, xuanzhuo@linux.alibaba.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, talgi@nvidia.com, hengqi@linux.alibaba.com, horms@kernel.org Subject: Re: [PATCH 1/2] dim: clear irq_moder on init failure Date: Thu, 8 Oct 2026 23:42:27 +0800 Message-ID: <20261008154227.10902-1-shijianlin11@foxmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261005185335.2f8e8b42@kernel.org> References: <8d6a637142c411f83771fda5b57bb4451651488b.1790751008.git.shijianlin11@foxmail.com> <20261005185335.2f8e8b42@kernel.org> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit You're right - there is no such sequence on current mainline. net_dim_init_irq_moder() has a single in-tree caller (virtio-net). If it fails, virtnet_probe() still does "goto free", which only ends in free_netdev(). Nothing calls net_dim_free_irq_moder() on that path, so the stale dev->irq_moder value is never dereferenced; it disappears when the net_device is freed. The dereference becomes reachable with the unwind change in patch 2: virtnet_init_irq_moder() -> net_dim_init_irq_moder() /* fails after kfree(moder); irq_moder stale */ goto free_irq_moder; /* patch 2 */ virtnet_free_irq_moder() net_dim_free_irq_moder() /* non-NULL irq_moder => */ rtnl_dereference(dev->irq_moder->rx_profile) /* UAF */ kfree(dev->irq_moder) /* freed again */ So patch 1 is not fixing a reachable bug on today's tree by itself; it is a hard prerequisite for patch 2. Without patch 1, patch 2 would trade the virtqueue leak for UAF (and a second kfree of moder) on this error path. I can add this call chain to the patch 1 commit message in v2 if you prefer. Jianlin