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[1/2] xfs: limit entries returned when counting fsmap records

Message ID 160192209042.2569942.5823795765306349583.stgit@magnolia (mailing list archive)
State Accepted, archived
Headers show
Series xfs: a few fixes and cleanups to GETFSMAP | expand

Commit Message

Darrick J. Wong Oct. 5, 2020, 6:21 p.m. UTC 
From: Darrick J. Wong <darrick.wong@oracle.com>

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>
---
 fs/xfs/xfs_fsmap.c |    3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
index 4eebcec4aae6..aa36e7daf82c 100644
--- a/fs/xfs/xfs_fsmap.c
+++ b/fs/xfs/xfs_fsmap.c
@@ -256,6 +256,9 @@  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++;