From fe89cf78648bf9f87b7fb26c4a7d3bc410718f06 Mon Sep 17 00:00:00 2001 From: Phillip Lougher Date: Sat, 30 Dec 2006 18:28:06 -0500 Subject: [PATCH] [PATCH] corrupted cramfs filesystems cause kernel oops (CVE-2006-5823) 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Chris Wright --- fs/cramfs/inode.c | 2 ++ 1 file changed, 2 insertions(+) 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, -- 2.47.3