add-bitmap-block-validity-checks

   1 ext4: add validity checks for bitmap block numbers
   2
   3 https://bugzilla.kernel.org/show_bug.cgi?id=199181
   4
   5 Reported-by: Wen Xu <wen.xu@gatech.edu>
   6 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
   7 Cc: stable@vger.kernel.org
   8 ---
   9  fs/ext4/balloc.c | 16 ++++++++++++++--
  10  fs/ext4/ialloc.c |  7 +++++++
  11  2 files changed, 21 insertions(+), 2 deletions(-)
  12
  13 diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
  14 index f82c4966f4ce..a33d8fb1bf2a 100644
  15 --- a/fs/ext4/balloc.c
  16 +++ b/fs/ext4/balloc.c
  17 @@ -338,20 +338,25 @@ static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
  18         /* check whether block bitmap block number is set */
  19         blk = ext4_block_bitmap(sb, desc);
  20         offset = blk - group_first_block;
  21 -       if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
  22 +       if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize ||
  23 +           !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
  24                 /* bad block bitmap */
  25                 return blk;
  26
  27         /* check whether the inode bitmap block number is set */
  28         blk = ext4_inode_bitmap(sb, desc);
  29         offset = blk - group_first_block;
  30 -       if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
  31 +       if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize ||
  32 +           !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
  33                 /* bad block bitmap */
  34                 return blk;
  35
  36         /* check whether the inode table block number is set */
  37         blk = ext4_inode_table(sb, desc);
  38         offset = blk - group_first_block;
  39 +       if (offset < 0 || EXT4_B2C(sbi, offset) >= sb->s_blocksize ||
  40 +           EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= sb->s_blocksize)
  41 +               return blk;
  42         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
  43                         EXT4_B2C(sbi, offset + sbi->s_itb_per_group),
  44                         EXT4_B2C(sbi, offset));
  45 @@ -417,6 +422,7 @@ struct buffer_head *
  46  ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
  47  {
  48         struct ext4_group_desc *desc;
  49 +       struct ext4_sb_info *sbi = EXT4_SB(sb);
  50         struct buffer_head *bh;
  51         ext4_fsblk_t bitmap_blk;
  52         int err;
  53 @@ -425,6 +431,12 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
  54         if (!desc)
  55                 return ERR_PTR(-EFSCORRUPTED);
  56         bitmap_blk = ext4_block_bitmap(sb, desc);
  57 +       if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
  58 +           (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
  59 +               ext4_error(sb, "Invalid block bitmap block %llu in "
  60 +                          "block_group %u", bitmap_blk, block_group);
  61 +               return ERR_PTR(-EFSCORRUPTED);
  62 +       }
  63         bh = sb_getblk(sb, bitmap_blk);
  64         if (unlikely(!bh)) {
  65                 ext4_error(sb, "Cannot get buffer for block bitmap - "
  66 diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
  67 index 3fa93665b4a3..df92e3ec9913 100644
  68 --- a/fs/ext4/ialloc.c
  69 +++ b/fs/ext4/ialloc.c
  70 @@ -122,6 +122,7 @@ static struct buffer_head *
  71  ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
  72  {
  73         struct ext4_group_desc *desc;
  74 +       struct ext4_sb_info *sbi = EXT4_SB(sb);
  75         struct buffer_head *bh = NULL;
  76         ext4_fsblk_t bitmap_blk;
  77         int err;
  78 @@ -131,6 +132,12 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
  79                 return ERR_PTR(-EFSCORRUPTED);
  80
  81         bitmap_blk = ext4_inode_bitmap(sb, desc);
  82 +       if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
  83 +           (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
  84 +               ext4_error(sb, "Invalid inode bitmap blk %llu in "
  85 +                          "block_group %u", bitmap_blk, block_group);
  86 +               return ERR_PTR(-EFSCORRUPTED);
  87 +       }
  88         bh = sb_getblk(sb, bitmap_blk);
  89         if (unlikely(!bh)) {
  90                 ext4_error(sb, "Cannot read inode bitmap - "