[PATCH 3.10 003/268] ext4: use more strict checks for inodes_per_block on mount

Willy Tarreau
2017-06-19T18:33:44Z

From: Theodore Ts'o <tytso@mit.edu>

commit cd6bb35bf7f6d7d922509bf50265383a0ceabe96 upstream.

Centralize the checks for inodes_per_block and be more strict to make
sure the inodes_per_block_group can't end up being zero.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
fs/ext4/super.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index faa1920..1afb7ac 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3614,12 +3614,16 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)

sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
- if (EXT4_INODE_SIZE(sb) == 0 || EXT4_INODES_PER_GROUP(sb) == 0)
- goto cantfind_ext4;

sbi->s_inodes_per_block = blocksize / EXT4_INODE_SIZE(sb);
if (sbi->s_inodes_per_block == 0)
goto cantfind_ext4;
+ if (sbi->s_inodes_per_group < sbi->s_inodes_per_block ||
+ sbi->s_inodes_per_group > blocksize * 8) {
+ ext4_msg(sb, KERN_ERR, "invalid inodes per group: %lu\n",
+ sbi->s_blocks_per_group);
+ goto failed_mount;
+ }
sbi->s_itb_per_group = sbi->s_inodes_per_group /
sbi->s_inodes_per_block;
sbi->s_desc_per_block = blocksize / EXT4_DESC_SIZE(sb);
@@ -3703,13 +3707,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
}
sbi->s_cluster_ratio = clustersize / blocksize;

- if (sbi->s_inodes_per_group > blocksize * 8) {
- ext4_msg(sb, KERN_ERR,
- "#inodes per group too big: %lu",
- sbi->s_inodes_per_group);
- goto failed_mount;
- }
-
/* Do we have standard group size of clustersize * 8 blocks ? */
if (sbi->s_blocks_per_group == clustersize << 3)
set_opt2(sb, STD_GROUP_SIZE);
--
2.8.0.rc2.1.gbe9624a