virtio: Sanitize config accesses

The handling of VIRTIO_PCI_O_CONFIG is prone to buffer access overflows.
This patch sanitizes this operation by using the newly added virtio op
get_config_size. Any access which goes beyond the config structure's
size is prevented and a failure is returned.

Additionally, PCI accesses which span more than a single byte are prevented
and a warning is printed because the implementation does not currently
support the behavior correctly.

Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Martin Radev <martin.b.radev@gmail.com>
Link: https://lore.kernel.org/r/20220509203940.754644-5-martin.b.radev@gmail.com
Signed-off-by: Will Deacon <will@kernel.org>
12 files changed