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 02888343D7B for ; Sat, 28 Feb 2026 18:10:58 +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=1772302258; cv=none; b=gxlWwXjc4p6io8JQDAGIt0ur6qeCOaHRirWqy5w1+StVAVOZiSu0lgtWB2HIQb2uWA3KsV/r3LNpqZ5qhGXQ3e4aSqP8Mi5opU2S7ojRjK4B6brpDsJ+uSv3kvUIIJueVOk+1fnh1llPsExdBxvghgS4S1aI8yvi0iaOpDUwtT8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772302258; c=relaxed/simple; bh=cIvM9cZQaVaOB3m0J80SmQTu4cZVnB3I0GrT4F4cUmQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wmo1qb3WExvWqqrWoE/Toql2rwwkPqlSN/UrPdhHCG4rxF1QIokj1rXSTMN0WpAM3cB5G9PK4F6wlQB+SpznLtywTqwB4mwmrTinexIgZk7A/cLovk8mPwk6WE3M+KXxsMCcVFCxnoFpMli6QMWNbCi8rgljBQmoDla9aZNkAYI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lux5gAQ5; 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="lux5gAQ5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F96FC116D0; Sat, 28 Feb 2026 18:10:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772302257; bh=cIvM9cZQaVaOB3m0J80SmQTu4cZVnB3I0GrT4F4cUmQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lux5gAQ5jQYDFSJlaPUkkS3PJX+3BUPA58Rm336awQ1PBE6gugymzyPXBgrlsc/YS 6es+y6S20eEqYDtKY8o1RoJzrV3n5DCVzxo8CHmWINOViokI2BzcTe60Q9ygcGkZa7 R7GGN1EcXKtMSqKVBAft7Mem2vxKPkqJR58MytZWfkqxFbUYkxkZlKPzsCmcCmiz9G D2Br8+HPgSUBqtiN6WPfly6CYNBOApVv2WX4wFQFm3NhFOC0IYt+Il/SN3sxCrMDdP RZx5lua/J2fyQPZAlNK1gRdFhQ7wVwucpOVzU1VKaQF7sPMlPo/Lcz0DWeVPsJgVNl QHrLbK8CZ/Uvg== From: Sasha Levin To: patches@lists.linux.dev Cc: Ziyi Guo , Juergen Gross , Paolo Abeni , Sasha Levin Subject: [PATCH 6.6 272/283] xen-netback: reject zero-queue configuration from guest Date: Sat, 28 Feb 2026 13:06:54 -0500 Message-ID: <20260228180709.1583486-272-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228180709.1583486-1-sashal@kernel.org> References: <20260228180709.1583486-1-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 a78a25b872409..61b547aab286a 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