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
Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name ext4-always-initialize-the-crc32c-checksum-driver.patch

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 26adff002e89c87e28c30f4f22c94689143012e6..01d318831dd5a081f75c86435814b64f6f5d66fe 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3489,15 +3489,12 @@ 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 */