[PATCH] corrupted cramfs filesystems cause kernel oops
authorPhillip Lougher <phillip@lougher.org.uk>
Thu, 7 Dec 2006 04:37:20 +0000 (20:37 -0800)
committerLinus Torvalds <torvalds@woody.osdl.org>
Thu, 7 Dec 2006 16:39:36 +0000 (08:39 -0800)
commit8bb0269160df2a60764013994d0bc5165406cf4a
tree1d91813ab99469213ee72afe90e7341a58a7fa79
parent2e591bbc0d563e12f5a260fbbca0df7d5810910e
[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>
fs/cramfs/inode.c