On Tue, 17 Jul 2018 12:39:00 -0500 "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> 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/vfio/pci/vfio_pci.c:734 vfio_pci_ioctl() > warn: potential spectre issue 'vdev->region' > > Fix this by sanitizing info.index before indirectly using it to index > 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@xxxxxxxxxxxxxxx > Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> > --- > drivers/vfio/pci/vfio_pci.c | 4 ++++ > 1 file changed, 4 insertions(+) Applied to vfio for-linus branch for v4.18. Thanks! Alex > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c > index b423a30..125b58e 100644 > --- a/drivers/vfio/pci/vfio_pci.c > +++ b/drivers/vfio/pci/vfio_pci.c > @@ -28,6 +28,7 @@ > #include <linux/uaccess.h> > #include <linux/vfio.h> > #include <linux/vgaarb.h> > +#include <linux/nospec.h> > > #include "vfio_pci_private.h" > > @@ -727,6 +728,9 @@ static long vfio_pci_ioctl(void *device_data, > if (info.index >= > VFIO_PCI_NUM_REGIONS + vdev->num_regions) > return -EINVAL; > + info.index = array_index_nospec(info.index, > + VFIO_PCI_NUM_REGIONS + > + vdev->num_regions); > > i = info.index - VFIO_PCI_NUM_REGIONS; >
