From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: "Theodore Ts'o" <tytso@mit.edu>, linux-ext4 <linux-ext4@vger.kernel.org>
Subject: [PATCH] ext4: limit entries returned when counting fsmap records
Date: Thu, 1 Oct 2020 15:21:48 -0700 [thread overview]
Message-ID: <20201001222148.GA49520@magnolia> (raw)
From: Darrick J. Wong <darrick.wong@oracle.com>
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: 0c9ec4beecac ("ext4: support GETFSMAP ioctls")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/ext4/fsmap.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/ext4/fsmap.c b/fs/ext4/fsmap.c
index dbccf46f1770..37347ba868b7 100644
--- a/fs/ext4/fsmap.c
+++ b/fs/ext4/fsmap.c
@@ -108,6 +108,9 @@ static int ext4_getfsmap_helper(struct super_block *sb,
/* Are we just counting mappings? */
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)
info->gfi_head->fmh_entries++;
next reply other threads:[~2020-10-01 22:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 22:21 Darrick J. Wong [this message]
2020-10-03 5:23 ` [PATCH] ext4: limit entries returned when counting fsmap records Theodore Y. Ts'o
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