[ 11/46] vfio-pci: Fix buffer overfill

Greg Kroah-Hartman
2013-01-24T21:35:29Z

From: Alex Williamson <alex.williamson@redhat.com>

commit ec1287e511320a2c9a02640b7ac02d5d79f56f08 upstream.

A read from a range hidden from the user (ex. MSI-X vector table)
attempts to fill the user buffer up to the end of the excluded range
instead of up to the requested count. Fix it.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/vfio/pci/vfio_pci_rdwr.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -240,17 +240,17 @@ ssize_t vfio_pci_mem_readwrite(struct vf
filled = 1;
} else {
/* Drop writes, fill reads with FF */
+ filled = min((size_t)(x_end - pos), count);
if (!iswrite) {
char val = 0xFF;
size_t i;

- for (i = 0; i < x_end - pos; i++) {
+ for (i = 0; i < filled; i++) {
if (put_user(val, buf + i))
goto out;
}
}

- filled = x_end - pos;
}

count -= filled;