The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a45403b51582a87872927a3e0fc0a389c26867f1 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o <tytso@xxxxxxx> Date: Thu, 29 Mar 2018 22:10:31 -0400 Subject: [PATCH] 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@xxxxxxx> Cc: stable@xxxxxxxxxxxxxxx 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 */