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| author | Phillip Lougher <phillip@lougher.org.uk> | 2006-12-06 20:37:20 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-07 08:39:36 -0800 |
| commit | 8bb0269160df2a60764013994d0bc5165406cf4a (patch) | |
| tree | 1d91813ab99469213ee72afe90e7341a58a7fa79 /fs/cramfs | |
| parent | 2e591bbc0d563e12f5a260fbbca0df7d5810910e (diff) | |
| download | lwn-8bb0269160df2a60764013994d0bc5165406cf4a.tar.gz lwn-8bb0269160df2a60764013994d0bc5165406cf4a.zip | |
[PATCH] corrupted cramfs filesystems cause kernel oops
Steve Grubb's fzfuzzer tool (http://people.redhat.com/sgrubb/files/
fsfuzzer-0.6.tar.gz) generates corrupt Cramfs filesystems which cause
Cramfs to kernel oops in cramfs_uncompress_block(). The cause of the oops
is an unchecked corrupted block length field read by cramfs_readpage().
This patch adds a sanity check to cramfs_readpage() which checks that the
block length field is sensible. The (PAGE_CACHE_SIZE << 1) size check is
intentional, even though the uncompressed data is not going to be larger
than PAGE_CACHE_SIZE, gzip sometimes generates compressed data larger than
the original source data. Mkcramfs checks that the compressed size is
always less than or equal to PAGE_CACHE_SIZE << 1. Of course Cramfs could
use the original uncompressed data in this case, but it doesn't.
Signed-off-by: Phillip Lougher <phillip@lougher.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/cramfs')
| -rw-r--r-- | fs/cramfs/inode.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c index a624c3ec8189..0509cedd415c 100644 --- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -481,6 +481,8 @@ static int cramfs_readpage(struct file *file, struct page * page) pgdata = kmap(page); if (compr_len == 0) ; /* hole */ + else if (compr_len > (PAGE_CACHE_SIZE << 1)) + printk(KERN_ERR "cramfs: bad compressed blocksize %u\n", compr_len); else { mutex_lock(&read_mutex); bytes_filled = cramfs_uncompress_block(pgdata, |