From: Darrick J. Wong <darrick.wong@oracle.com>
Date: Thu, 1 Oct 2020 17:56:07 +0000 (-0700)
Subject: xfs: limit entries returned when counting fsmap records
X-Git-Tag: v5.10-rc1~30^2~10
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=acd1ac3aa22fd58803a12d26b1ab7f70232f8d8d;p=linux-block.git

xfs: limit entries returned when counting fsmap records

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>
---

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++;