always-load-checksum-driver

   1 ext4: always initialize the crc32c checksum driver
   2
   3 The extended attribute code now uses the crc32c checksum for hashing
   4 purposes, so we should just always always initialize it.  We also want
   5 to prevent NULL pointer dereferences if one of the metadata checksum
   6 features is enabled after the file sytsem is originally mounted.
   7
   8 This issue has been assigned CVE-2018-1094.
   9
  10 https://bugzilla.kernel.org/show_bug.cgi?id=199183
  11 https://bugzilla.redhat.com/show_bug.cgi?id=1560788
  12
  13 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  14 Cc: stable@vger.kernel.org
  15 ---
  16  fs/ext4/super.c | 15 ++++++---------
  17  1 file changed, 6 insertions(+), 9 deletions(-)
  18
  19 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
  20 index 9d1da40c1f62..7cd022c344d1 100644
  21 --- a/fs/ext4/super.c
  22 +++ b/fs/ext4/super.c
  23 @@ -3492,15 +3492,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
  24         }
  25
  26         /* Load the checksum driver */
  27 -       if (ext4_has_feature_metadata_csum(sb) ||
  28 -           ext4_has_feature_ea_inode(sb)) {
  29 -               sbi->s_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
  30 -               if (IS_ERR(sbi->s_chksum_driver)) {
  31 -                       ext4_msg(sb, KERN_ERR, "Cannot load crc32c driver.");
  32 -                       ret = PTR_ERR(sbi->s_chksum_driver);
  33 -                       sbi->s_chksum_driver = NULL;
  34 -                       goto failed_mount;
  35 -               }
  36 +       sbi->s_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
  37 +       if (IS_ERR(sbi->s_chksum_driver)) {
  38 +               ext4_msg(sb, KERN_ERR, "Cannot load crc32c driver.");
  39 +               ret = PTR_ERR(sbi->s_chksum_driver);
  40 +               sbi->s_chksum_driver = NULL;
  41 +               goto failed_mount;
  42         }
  43
  44         /* Check superblock checksum */