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ext4: sanity check the block and cluster size at mount time

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If the block size or cluster size is insane, reject the mount.  This
is important for security reasons (although we shouldn't be just
depending on this check).

Ref: http://www.securityfocus.com/archive/1/539661
Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1332506
Reported-by: Borislav Petkov <bp@alien8.de>
Reported-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
This commit is contained in:
Theodore Ts'o 2016-11-18 13:00:24 -05:00
parent 0f0909e242
commit 8cdf3372fe
2 changed files with 17 additions and 1 deletions
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1
fs/ext4/ext4.h
View file

@ -235,6 +235,7 @@ struct ext4_io_submit {
#define EXT4_MAX_BLOCK_SIZE 65536
#define EXT4_MIN_BLOCK_LOG_SIZE 10
#define EXT4_MAX_BLOCK_LOG_SIZE 16
#define EXT4_MAX_CLUSTER_LOG_SIZE 30
#ifdef __KERNEL__
# define EXT4_BLOCK_SIZE(s) ((s)->s_blocksize)
#else

17
fs/ext4/super.c
View file

@ -3565,7 +3565,15 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
if (blocksize < EXT4_MIN_BLOCK_SIZE ||
blocksize > EXT4_MAX_BLOCK_SIZE) {
ext4_msg(sb, KERN_ERR,
"Unsupported filesystem blocksize %d", blocksize);
"Unsupported filesystem blocksize %d (%d log_block_size)",
blocksize, le32_to_cpu(es->s_log_block_size));
goto failed_mount;
}
if (le32_to_cpu(es->s_log_block_size) >
(EXT4_MAX_BLOCK_LOG_SIZE - EXT4_MIN_BLOCK_LOG_SIZE)) {
ext4_msg(sb, KERN_ERR,
"Invalid log block size: %u",
le32_to_cpu(es->s_log_block_size));
goto failed_mount;
}
@ -3697,6 +3705,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
"block size (%d)", clustersize, blocksize);
goto failed_mount;
}
if (le32_to_cpu(es->s_log_cluster_size) >
(EXT4_MAX_CLUSTER_LOG_SIZE - EXT4_MIN_BLOCK_LOG_SIZE)) {
ext4_msg(sb, KERN_ERR,
"Invalid log cluster size: %u",
le32_to_cpu(es->s_log_cluster_size));
goto failed_mount;
}
sbi->s_cluster_bits = le32_to_cpu(es->s_log_cluster_size) -
le32_to_cpu(es->s_log_block_size);
sbi->s_clusters_per_group =