ext4: use more strict checks for inodes_per_block on mount

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 9 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5a60eecf4deb..2113aad08c89 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3660,12 +3660,16 @@ 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);
@@ -3748,13 +3752,6 @@ 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);