ext4: always initialize the crc32c checksum driver

The extended attribute code now uses the crc32c checksum for hashing
purposes, so we should just always always initialize it.  We also want
to prevent NULL pointer dereferences if one of the metadata checksum
features is enabled after the file sytsem is originally mounted.

This issue has been assigned CVE-2018-1094.

https://bugzilla.kernel.org/show_bug.cgi?id=199183
https://bugzilla.redhat.com/show_bug.cgi?id=1560788

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9d1da40c1f62bc26a2c029d5904490f6a654cad1..7cd022c344d1da9198ba71f3a2344fe1e47eca13 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3492,15 +3492,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
        }
 
        /* Load the checksum driver */
-       if (ext4_has_feature_metadata_csum(sb) ||
-           ext4_has_feature_ea_inode(sb)) {
-               sbi->s_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
-               if (IS_ERR(sbi->s_chksum_driver)) {
-                       ext4_msg(sb, KERN_ERR, "Cannot load crc32c driver.");
-                       ret = PTR_ERR(sbi->s_chksum_driver);
-                       sbi->s_chksum_driver = NULL;
-                       goto failed_mount;
-               }
+       sbi->s_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
+       if (IS_ERR(sbi->s_chksum_driver)) {
+               ext4_msg(sb, KERN_ERR, "Cannot load crc32c driver.");
+               ret = PTR_ERR(sbi->s_chksum_driver);
+               sbi->s_chksum_driver = NULL;
+               goto failed_mount;
        }
 
        /* Check superblock checksum */