[PATCH 6.1 097/236] gfs2: Fix invalid metadata access in punch_hole

Greg Kroah-Hartman
2024-05-14T11:31:58Z

From: Andrew Price <anprice@redhat.com>

[ Upstream commit c95346ac918c5badf51b9a7ac58a26d3bd5bb224 ]

In punch_hole(), when the offset lies in the final block for a given
height, there is no hole to punch, but the maximum size check fails to
detect that. Consequently, punch_hole() will try to punch a hole beyond
the end of the metadata and fail. Fix the maximum size check.

Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/gfs2/bmap.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index e7537fd305dd2..9ad11e5bf14c3 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -1702,7 +1702,8 @@ static int punch_hole(struct gfs2_inode *ip, u64 offset, u64 length)
struct buffer_head *dibh, *bh;
struct gfs2_holder rd_gh;
unsigned int bsize_shift = sdp->sd_sb.sb_bsize_shift;
- u64 lblock = (offset + (1 << bsize_shift) - 1) >> bsize_shift;
+ unsigned int bsize = 1 << bsize_shift;
+ u64 lblock = (offset + bsize - 1) >> bsize_shift;
__u16 start_list[GFS2_MAX_META_HEIGHT];
__u16 __end_list[GFS2_MAX_META_HEIGHT], *end_list = NULL;
unsigned int start_aligned, end_aligned;
@@ -1713,7 +1714,7 @@ static int punch_hole(struct gfs2_inode *ip, u64 offset, u64 length)
u64 prev_bnr = 0;
__be64 *start, *end;

- if (offset >= maxsize) {
+ if (offset + bsize - 1 >= maxsize) {
/*
* The starting point lies beyond the allocated meta-data;
* there are no blocks do deallocate.
--
2.43.0