From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0EC8C4CEC5 for ; Fri, 13 Sep 2019 13:09:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8254D2089F for ; Fri, 13 Sep 2019 13:09:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568380171; bh=bORrhSqK3pcJToWmKEo0Pa4DNQLJt2fCkk6U57wF2TA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=DOi7bhOb/WWcwXNf98Q+FafSDx5t63ZvF8AHSWobTxR3EgwWaWtElorcqWh+OkuIT kdFFXwBkYgEwNDpZu6ZZO6Ij6eWABIgXC1zz8LJ5MbyvTpI2BmTa6GHvxOXu+MZpS6 wTOw0sTEYCMY2tU0BRk1z7N0XcBVPoDkZ3mHcF30= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388525AbfIMNJa (ORCPT ); Fri, 13 Sep 2019 09:09:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:33984 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388498AbfIMNJY (ORCPT ); Fri, 13 Sep 2019 09:09:24 -0400 Received: from localhost (unknown [104.132.45.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 26E40206A5; Fri, 13 Sep 2019 13:09:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568380163; bh=bORrhSqK3pcJToWmKEo0Pa4DNQLJt2fCkk6U57wF2TA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VtizNrJ8jSyuPyMX8MhD7w0sTzLr3kOqwootL3llKYPOtPlvq2fLaKgxv9L+HOz5h NpssmusR30OjkUKqiL79goGdH+mhphsKALyLTxs/IavzNrS6UuatVMG7sARdmMSRiC oQlqWNZCy4Ot1PoT0E13d2/XwuCpAE+M+91llDRM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lidong Chen , ruippan , yongduan , "Michael S. Tsirkin" , Tyler Hicks Subject: [PATCH 4.9 14/14] vhost: make sure log_num < in_num Date: Fri, 13 Sep 2019 14:07:07 +0100 Message-Id: <20190913130446.949716002@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190913130440.264749443@linuxfoundation.org> References: <20190913130440.264749443@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: yongduan commit 060423bfdee3f8bc6e2c1bac97de24d5415e2bc4 upstream. The code assumes log_num < in_num everywhere, and that is true as long as in_num is incremented by descriptor iov count, and log_num by 1. However this breaks if there's a zero sized descriptor. As a result, if a malicious guest creates a vring desc with desc.len = 0, it may cause the host kernel to crash by overflowing the log array. This bug can be triggered during the VM migration. There's no need to log when desc.len = 0, so just don't increment log_num in this case. Fixes: 3a4d5c94e959 ("vhost_net: a kernel-level virtio server") Cc: stable@vger.kernel.org Reviewed-by: Lidong Chen Signed-off-by: ruippan Signed-off-by: yongduan Acked-by: Michael S. Tsirkin Reviewed-by: Tyler Hicks Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman --- drivers/vhost/vhost.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1989,7 +1989,7 @@ static int get_indirect(struct vhost_vir /* If this is an input descriptor, increment that count. */ if (access == VHOST_ACCESS_WO) { *in_num += ret; - if (unlikely(log)) { + if (unlikely(log && ret)) { log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); log[*log_num].len = vhost32_to_cpu(vq, desc.len); ++*log_num; @@ -2125,7 +2125,7 @@ int vhost_get_vq_desc(struct vhost_virtq /* If this is an input descriptor, * increment that count. */ *in_num += ret; - if (unlikely(log)) { + if (unlikely(log && ret)) { log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); log[*log_num].len = vhost32_to_cpu(vq, desc.len); ++*log_num;