[PATCH 4.14 093/191] xfs: limit entries returned when counting fsmap records

Greg Kroah-Hartman
2020-10-27T18:16:08Z

From: Darrick J. Wong <darrick.wong@oracle.com>

[ Upstream commit acd1ac3aa22fd58803a12d26b1ab7f70232f8d8d ]

If userspace asked fsmap to count the number of entries, we cannot
return more than UINT_MAX entries because fmh_entries is u32.
Therefore, stop counting if we hit this limit or else we will waste time
to return truncated results.

Fixes: e89c041338ed ("xfs: implement the GETFSMAP ioctl")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/xfs/xfs_fsmap.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
index 43cfc07996a43..e7622e0841868 100644
--- a/fs/xfs/xfs_fsmap.c
+++ b/fs/xfs/xfs_fsmap.c
@@ -273,6 +273,9 @@ xfs_getfsmap_helper(

/* Are we just counting mappings? */
if (info->head->fmh_count == 0) {
+ if (info->head->fmh_entries == UINT_MAX)
+ return -ECANCELED;
+
if (rec_daddr > info->next_daddr)
info->head->fmh_entries++;

--
2.25.1