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| author | Phillip Lougher <phillip@squashfs.org.uk> | 2012-03-09 03:02:59 +0000 |
|---|---|---|
| committer | Phillip Lougher <phillip@squashfs.org.uk> | 2012-03-10 03:01:02 +0000 |
| commit | 4b0180a49f08dd1c681cdc99edc9e0cec0a833fa (patch) | |
| tree | 816d9a9095b816683c8edc2089d510880fd59d35 /fs/squashfs | |
| parent | 2158d3fd2769546cd9004eaeb776fee946155238 (diff) | |
| download | linux-4b0180a49f08dd1c681cdc99edc9e0cec0a833fa.tar.bz2 | |
Squashfs: add mount time sanity check for block_size and block_log match
Squashfs currently has a sanity check for block_size less than or
equal to the maximum block_size (1 Mbyte). This catches some
superblock corruption, but obviously with a block_size maximum
of 1 Mbyte there's 7 correct values (4K, 8K, 16K, 32K, ... etc) and
a lot of incorrect values which are not caught by this check.
The Squashfs superblock, however, has both a block_size and
a block_log (2^block_log == block_size). Checking that the block_size
matches the block_log is a much more robust check. Corruption of the
superblock is unlikely to produce values which match, and it also
ensures the block_size is an exact power of two.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Diffstat (limited to 'fs/squashfs')
| -rw-r--r-- | fs/squashfs/super.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c index ecaa2f7bdb8f..a55a9c57be18 100644 --- a/fs/squashfs/super.c +++ b/fs/squashfs/super.c @@ -158,10 +158,15 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent) goto failed_mount; } + /* Check block log for sanity */ msblk->block_log = le16_to_cpu(sblk->block_log); if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) goto failed_mount; + /* Check that block_size and block_log match */ + if (msblk->block_size != (1 << msblk->block_log)) + goto failed_mount; + /* Check the root inode for sanity */ root_inode = le64_to_cpu(sblk->root_inode); if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) |