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ext4: limit entries returned when counting fsmap records

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If userspace asked fsmap to try 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: 0c9ec4beec ("ext4: support GETFSMAP ioctls")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Link: https://lore.kernel.org/r/20201001222148.GA49520@magnolia
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Darrick J. Wong 2020-10-01 15:21:48 -07:00 committed by Theodore Ts'o
parent addd752cff
commit af8c53c8bc
1 changed files with 3 additions and 0 deletions
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3
fs/ext4/fsmap.c
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@ -108,6 +108,9 @@ static int ext4_getfsmap_helper(struct super_block *sb,
/* Are we just counting mappings? */ /* Are we just counting mappings? */
if (info->gfi_head->fmh_count == 0) { if (info->gfi_head->fmh_count == 0) {
if (info->gfi_head->fmh_entries == UINT_MAX)
return EXT4_QUERY_RANGE_ABORT;
if (rec_fsblk > info->gfi_next_fsblk) if (rec_fsblk > info->gfi_next_fsblk)
info->gfi_head->fmh_entries++; info->gfi_head->fmh_entries++;