From a45403b51582a87872927a3e0fc0a389c26867f1 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 29 Mar 2018 22:10:31 -0400
Subject: [PATCH] ext4: always initialize the crc32c checksum driver
Git-commit: a45403b51582a87872927a3e0fc0a389c26867f1
Patch-mainline: v4.17-rc1
References: bsc#1087007 cve-2018-1094

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
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/ext4/super.c |   15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3473,15 +3473,12 @@ static int ext4_fill_super(struct super_
 		goto cantfind_ext4;
 	}
 
-	/* Load the checksum driver */
-	if (ext4_has_feature_metadata_csum(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 */