xfs: fix over-copying of getbmap parameters from userspace

commit be6324c00c4d1e0e665f03ed1fc18863a88da119 upstream.

In xfs_ioc_getbmap, we should only copy the fields of struct getbmap
from userspace, or else we end up copying random stack contents into the
kernel.  struct getbmap is a strict subset of getbmapx, so a partial
structure copy should work fine.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Darrick J. Wong 2017-04-03 15:17:57 -07:00 committed by Greg Kroah-Hartman
parent c2ad2dc3d2
commit de417ea6b0

View File

@ -1542,10 +1542,11 @@ xfs_ioc_getbmap(
unsigned int cmd,
void __user *arg)
{
struct getbmapx bmx;
struct getbmapx bmx = { 0 };
int error;
if (copy_from_user(&bmx, arg, sizeof(struct getbmapx)))
/* struct getbmap is a strict subset of struct getbmapx. */
if (copy_from_user(&bmx, arg, offsetof(struct getbmapx, bmv_iflags)))
return -EFAULT;
if (bmx.bmv_count < 2)