fix-oops-when-loading-block-bitmap-failed

   1 ext4: fix oops when loading block bitmap failed
   2
   3 From: Jan Kara <jack@suse.cz>
   4
   5 When we fail to load block bitmap in __ext4_new_inode() we will
   6 dereference NULL pointer in ext4_journal_get_write_access(). So check
   7 for error from ext4_read_block_bitmap().
   8
   9 Coverity-id: 989065
  10 Cc: stable@vger.kernel.org
  11 Signed-off-by: Jan Kara <jack@suse.cz>
  12 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  13 ---
  14  fs/ext4/ialloc.c | 4 ++++
  15  1 file changed, 4 insertions(+)
  16
  17 diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
  18 index 8012a5daf401..ac644c31ca67 100644
  19 --- a/fs/ext4/ialloc.c
  20 +++ b/fs/ext4/ialloc.c
  21 @@ -887,6 +887,10 @@ got:
  22                 struct buffer_head *block_bitmap_bh;
  23
  24                 block_bitmap_bh = ext4_read_block_bitmap(sb, group);
  25 +               if (!block_bitmap_bh) {
  26 +                       err = -EIO;
  27 +                       goto out;
  28 +               }
  29                 BUFFER_TRACE(block_bitmap_bh, "get block bitmap access");
  30                 err = ext4_journal_get_write_access(handle, block_bitmap_bh);
  31                 if (err) {
  32 --
  33 1.8.1.4
  34
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