From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:57100 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727875AbeHWMkb (ORCPT ); Thu, 23 Aug 2018 08:40:31 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Gustavo A. R. Silva" , Zhenyu Wang Subject: [PATCH 4.18 09/22] drm/i915/kvmgt: Fix potential Spectre v1 Date: Thu, 23 Aug 2018 09:56:35 +0200 Message-Id: <20180823074759.753464908@linuxfoundation.org> In-Reply-To: <20180823074759.234685844@linuxfoundation.org> References: <20180823074759.234685844@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gustavo A. R. Silva commit de5372da605d3bca46e3102bab51b7e1c0e0a6f6 upstream. info.index can be indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/gpu/drm/i915/gvt/kvmgt.c:1232 intel_vgpu_ioctl() warn: potential spectre issue 'vgpu->vdev.region' [r] Fix this by sanitizing info.index before indirectly using it to index vgpu->vdev.region Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva Signed-off-by: Zhenyu Wang Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/gvt/kvmgt.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/drivers/gpu/drm/i915/gvt/kvmgt.c +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c @@ -43,6 +43,8 @@ #include #include +#include + #include "i915_drv.h" #include "gvt.h" @@ -1084,7 +1086,8 @@ static long intel_vgpu_ioctl(struct mdev } else if (cmd == VFIO_DEVICE_GET_REGION_INFO) { struct vfio_region_info info; struct vfio_info_cap caps = { .buf = NULL, .size = 0 }; - int i, ret; + unsigned int i; + int ret; struct vfio_region_info_cap_sparse_mmap *sparse = NULL; size_t size; int nr_areas = 1; @@ -1169,6 +1172,10 @@ static long intel_vgpu_ioctl(struct mdev if (info.index >= VFIO_PCI_NUM_REGIONS + vgpu->vdev.num_regions) return -EINVAL; + info.index = + array_index_nospec(info.index, + VFIO_PCI_NUM_REGIONS + + vgpu->vdev.num_regions); i = info.index - VFIO_PCI_NUM_REGIONS;