vfio/pci: Fix potential Spectre v1
authorGustavo A. R. Silva <gustavo@embeddedor.com>
Tue, 17 Jul 2018 17:39:00 +0000 (12:39 -0500)
committerAlex Williamson <alex.williamson@redhat.com>
Wed, 18 Jul 2018 18:57:25 +0000 (12:57 -0600)
commit0e714d27786ce1fb3efa9aac58abc096e68b1c2a
tree0d46cee8004e651a4cab9262d43373f630c23026
parent9d3cce1e8b8561fed5f383d22a4d6949db4eadbe
vfio/pci: Fix potential Spectre v1

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>
drivers/vfio/pci/vfio_pci.c