From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 85A3335AC28 for ; Sat, 28 Feb 2026 18:19:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772302768; cv=none; b=cHoS/S3LlBN1HmDgnwhLnZOcCwV/UDd4dcJ9bKdpbJkqJGUhQn+KP8ZY2ZMwmOzNxhlP6bcdBnf4Hxdz/ceXcHuguKtwdTKDI1kc+kMN2FtHDdnjVM4DHhIZJZCSj/+zi4HcrU6M9Uh5E4QNwBBVbO/HvMEpWsOyToHpzXRX+Ew= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772302768; c=relaxed/simple; bh=0QX6fx5ztsOwbqkdDSx3cDlN5iFEkWOFNLENrERXWbE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=awRmGbL4VXLmhVx8gnzp6ZLMdcq9quD50SH0IlcdDq8Pi70T7LOJqeQ42TSLuMezmDxXs6O/RgDZl6mMSehLzpzHh/0IR1W+clCSXxx0htunSRisOJVdU76rSzz5jenracJx7zYYPbh+XAY3iG7D1xVwyRbjIr22WUzTMTh6wSA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u9UGHZdK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="u9UGHZdK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CFE28C2BCB0; Sat, 28 Feb 2026 18:19:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772302768; bh=0QX6fx5ztsOwbqkdDSx3cDlN5iFEkWOFNLENrERXWbE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u9UGHZdKZsRK6dHPT4KXRvyYNfe/z6naHdWaJNyd1tt5Vb3L52UOYSDQU/pPQ0f8J THn2haHw7a6kLgYFcn7OC4yYSTAkamhfGOt0MP0BneGdwLSc3gsYLVc9QtpAjd57Wp DSJZ5cfGDxsdCjKO5hLUn8v8nf97Dj6cm15RdhvjP1zZMGnypaugzi2zyPV920WPxz 5kG0w96CHg0xrAzbUNpANpASSR7b2otaj6h5kVbQXg3LGHwf2qxGnViBUgi4WMUYzV /CyOuzDQjFQGx74J6n+3ODjO7l/hORp9rpcD6NyT9N1gEFX+qZsn5W9JoXnaGxbfV6 ej5y/voMSZG1A== From: Sasha Levin To: patches@lists.linux.dev Cc: Ziyi Guo , Juergen Gross , Paolo Abeni , Sasha Levin Subject: [PATCH 5.10 140/147] xen-netback: reject zero-queue configuration from guest Date: Sat, 28 Feb 2026 13:17:28 -0500 Message-ID: <20260228181736.1605592-140-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228181736.1605592-1-sashal@kernel.org> References: <20260228181736.1605592-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Ziyi Guo [ Upstream commit 6d1dc8014334c7fb25719999bca84d811e60a559 ] A malicious or buggy Xen guest can write "0" to the xenbus key "multi-queue-num-queues". The connect() function in the backend only validates the upper bound (requested_num_queues > xenvif_max_queues) but not zero, allowing requested_num_queues=0 to reach vzalloc(array_size(0, sizeof(struct xenvif_queue))), which triggers WARN_ON_ONCE(!size) in __vmalloc_node_range(). On systems with panic_on_warn=1, this allows a guest-to-host denial of service. The Xen network interface specification requires the queue count to be "greater than zero". Add a zero check to match the validation already present in xen-blkback, which has included this guard since its multi-queue support was added. Fixes: 8d3d53b3e433 ("xen-netback: Add support for multiple queues") Signed-off-by: Ziyi Guo Reviewed-by: Juergen Gross Link: https://patch.msgid.link/20260212224040.86674-1-n7l8m4@u.northwestern.edu Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- drivers/net/xen-netback/xenbus.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c index 9ee9ce0493fe6..c47e327039a0a 100644 --- a/drivers/net/xen-netback/xenbus.c +++ b/drivers/net/xen-netback/xenbus.c @@ -735,10 +735,11 @@ static void connect(struct backend_info *be) */ requested_num_queues = xenbus_read_unsigned(dev->otherend, "multi-queue-num-queues", 1); - if (requested_num_queues > xenvif_max_queues) { + if (requested_num_queues > xenvif_max_queues || + requested_num_queues == 0) { /* buggy or malicious guest */ xenbus_dev_fatal(dev, -EINVAL, - "guest requested %u queues, exceeding the maximum of %u.", + "guest requested %u queues, but valid range is 1 - %u.", requested_num_queues, xenvif_max_queues); return; } -- 2.51.0