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xfs: fix over-copying of getbmap parameters from userspace

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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>
This commit is contained in:
Darrick J. Wong 2017-04-03 15:17:57 -07:00
parent 422e5b53ed
commit be6324c00c
1 changed files with 3 additions and 2 deletions
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5
fs/xfs/xfs_ioctl.c
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@ -1543,10 +1543,11 @@ 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)