verify-inodes_per_group-during-mount

   1 ext4: use more strict checks for inodes_per_block on mount
   2
   3 Centralize the checks for inodes_per_block and be more strict to make
   4 sure the inodes_per_block_group can't end up being zero.
   5
   6 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
   7 Reviewed-by: Andreas Dilger <adilger@dilger.ca>
   8 Cc: stable@vger.kernel.org
   9 ---
  10  fs/ext4/super.c | 15 ++++++---------
  11  1 file changed, 6 insertions(+), 9 deletions(-)
  12
  13 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
  14 index 404e6f3c1bed..689c02df1af4 100644
  15 --- a/fs/ext4/super.c
  16 +++ b/fs/ext4/super.c
  17 @@ -3668,12 +3668,16 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
  18
  19         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
  20         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
  21 -       if (EXT4_INODE_SIZE(sb) == 0 || EXT4_INODES_PER_GROUP(sb) == 0)
  22 -               goto cantfind_ext4;
  23
  24         sbi->s_inodes_per_block = blocksize / EXT4_INODE_SIZE(sb);
  25         if (sbi->s_inodes_per_block == 0)
  26                 goto cantfind_ext4;
  27 +       if (sbi->s_inodes_per_group < sbi->s_inodes_per_block ||
  28 +           sbi->s_inodes_per_group > blocksize * 8) {
  29 +               ext4_msg(sb, KERN_ERR, "invalid inodes per group: %lu\n",
  30 +                        sbi->s_blocks_per_group);
  31 +               goto failed_mount;
  32 +       }
  33         sbi->s_itb_per_group = sbi->s_inodes_per_group /
  34                                         sbi->s_inodes_per_block;
  35         sbi->s_desc_per_block = blocksize / EXT4_DESC_SIZE(sb);
  36 @@ -3756,13 +3760,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
  37         }
  38         sbi->s_cluster_ratio = clustersize / blocksize;
  39
  40 -       if (sbi->s_inodes_per_group > blocksize * 8) {
  41 -               ext4_msg(sb, KERN_ERR,
  42 -                      "#inodes per group too big: %lu",
  43 -                      sbi->s_inodes_per_group);
  44 -               goto failed_mount;
  45 -       }
  46 -
  47         /* Do we have standard group size of clustersize * 8 blocks ? */
  48         if (sbi->s_blocks_per_group == clustersize << 3)
  49                 set_opt2(sb, STD_GROUP_SIZE);