[PATCH 4.11 115/115] xfs: Fix off-by-in in loop termination in xfs_find_get_desired_pgoff()

Greg Kroah-Hartman
2017-06-05T16:34:08Z

From: Jan Kara <jack@suse.cz>

commit d7fd24257aa60316bf81093f7f909dc9475ae974 upstream.

There is an off-by-one error in loop termination conditions in
xfs_find_get_desired_pgoff() since 'end' may index a page beyond end of
desired range if 'endoff' is page aligned. It doesn't have any visible
effects but still it is good to fix it.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/xfs_file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1043,7 +1043,7 @@ xfs_find_get_desired_pgoff(

index = startoff >> PAGE_SHIFT;
endoff = XFS_FSB_TO_B(mp, map->br_startoff + map->br_blockcount);
- end = endoff >> PAGE_SHIFT;
+ end = (endoff - 1) >> PAGE_SHIFT;
do {
int want;
unsigned nr_pages;