On 2018.08.02 22:40:19 -0500, Gustavo A. R. Silva wrote: > 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 Thanks for catching this! Applied. > > 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@xxxxxxxxxxxxxxx > Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/gvt/kvmgt.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c > index 4d2f53a..b703f20 100644 > --- a/drivers/gpu/drm/i915/gvt/kvmgt.c > +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c > @@ -43,6 +43,8 @@ > #include <linux/mdev.h> > #include <linux/debugfs.h> > > +#include <linux/nospec.h> > + > #include "i915_drv.h" > #include "gvt.h" > > @@ -1139,7 +1141,8 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd, > } 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; > @@ -1224,6 +1227,10 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd, > 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; > > -- > 2.7.4 > > _______________________________________________ > intel-gvt-dev mailing list > intel-gvt-dev@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gvt-dev -- Open Source Technology Center, Intel ltd. $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827
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