4.17-stable review patch. If anyone has any objections, please let me know.
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From: Gustavo A. R. Silva gustavo@embeddedor.com
commit 0e714d27786ce1fb3efa9aac58abc096e68b1c2a 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/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@vger.kernel.org Signed-off-by: Gustavo A. R. Silva gustavo@embeddedor.com Signed-off-by: Alex Williamson alex.williamson@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/vfio/pci/vfio_pci.c | 4 ++++ 1 file changed, 4 insertions(+)
--- 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_ 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;