releases/3.14.44/ext4-check-for-zero-length-extent-explicitly.patch

   1 From 2f974865ffdfe7b9f46a9940836c8b167342563d Mon Sep 17 00:00:00 2001
   2 From: Eryu Guan <guaneryu@gmail.com>
   3 Date: Thu, 14 May 2015 19:00:45 -0400
   4 Subject: ext4: check for zero length extent explicitly
   5
   6 From: Eryu Guan <guaneryu@gmail.com>
   7
   8 commit 2f974865ffdfe7b9f46a9940836c8b167342563d upstream.
   9
  10 The following commit introduced a bug when checking for zero length extent
  11
  12 5946d08 ext4: check for overlapping extents in ext4_valid_extent_entries()
  13
  14 Zero length extent could pass the check if lblock is zero.
  15
  16 Adding the explicit check for zero length back.
  17
  18 Signed-off-by: Eryu Guan <guaneryu@gmail.com>
  19 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21
  22 ---
  23  fs/ext4/extents.c |    2 +-
  24  1 file changed, 1 insertion(+), 1 deletion(-)
  25
  26 --- a/fs/ext4/extents.c
  27 +++ b/fs/ext4/extents.c
  28 @@ -361,7 +361,7 @@ static int ext4_valid_extent(struct inod
  29         ext4_lblk_t lblock = le32_to_cpu(ext->ee_block);
  30         ext4_lblk_t last = lblock + len - 1;
  31
  32 -       if (lblock > last)
  33 +       if (len == 0 || lblock > last)
  34                 return 0;
  35         return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, len);
  36  }