From f2f616f3e333ad62f80495658a6a60ea5524ebab Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Thu, 1 Oct 2020 15:21:48 -0700 Subject: [PATCH] ext4: limit entries returned when counting fsmap records [ Upstream commit af8c53c8bc087459b1aadd4c94805d8272358d79 ] 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 Link: https://lore.kernel.org/r/20201001222148.GA49520@magnolia Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- 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++;