add-sanity-check-to-ext4_get_group_info

   1 ext4: add sanity check to ext4_get_group_info()
   2
   3 The group number passed to ext4_get_group_info() should be valid, but
   4 let's add an assert to check this before we start creating a pointer
   5 based on that group number and dereferencing it.
   6
   7 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
   8 diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
   9 index bd9890f..f85f1fb 100644
  10 --- a/fs/ext4/ext4.h
  11 +++ b/fs/ext4/ext4.h
  12 @@ -2313,6 +2313,7 @@ struct ext4_group_info *ext4_get_group_info(struct super_block *sb,
  13  {
  14          struct ext4_group_info ***grp_info;
  15          long indexv, indexh;
  16 +        BUG_ON(group >= EXT4_SB(sb)->s_groups_count);
  17          grp_info = EXT4_SB(sb)->s_group_info;
  18          indexv = group >> (EXT4_DESC_PER_BLOCK_BITS(sb));
  19          indexh = group & ((EXT4_DESC_PER_BLOCK(sb)) - 1);