linux-ext4 - [PATCH 1/2] ext4: always initialize the crc32c checksum driver

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Message-Id: <20180326044906.13286-1-tytso@mit.edu>
Date:   Mon, 26 Mar 2018 00:49:05 -0400
From:   Theodore Ts'o <tytso@....edu>
To:     Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:     Theodore Ts'o <tytso@....edu>, stable@...r.kernel.org
Subject: [PATCH 1/2] 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.

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

Signed-off-by: Theodore Ts'o <tytso@....edu>
Cc: stable@...r.kernel.org
---
 fs/ext4/super.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9d1da40c1f62..7cd022c344d1 100644
--- 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 */
-- 
2.16.1.72.g5be1f00a9a