From: Phillip Lougher Date: Mon, 8 Jan 2007 06:02:45 +0000 (+0100) Subject: corrupted cramfs filesystems cause kernel oops (CVE-2006-5823) X-Git-Tag: v2.6.16.38-rc1~10 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d1f34c8e3fa155c1ae9599cd67a60debac66f6c0;p=karo-tx-linux.git 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: Adrian Bunk --- diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c index 8ad52f5bf255..30fdd5dc73bd 100644 --- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -482,6 +482,8 @@ 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 { down(&read_mutex); bytes_filled = cramfs_uncompress_block(pgdata,