From: Jan Kara <jack@suse.cz>
Date: Mon, 18 Oct 2021 10:37:41 +0000 (+0200)
Subject: isofs: Fix out of bound access for corrupted isofs image
X-Git-Tag: v4.4.292~10
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=156ce5bb6cc43a80a743810199defb1dc3f55b7f;p=thirdparty%2Fkernel%2Fstable.git

isofs: Fix out of bound access for corrupted isofs image

commit e96a1866b40570b5950cda8602c2819189c62a48 upstream.

When isofs image is suitably corrupted isofs_read_inode() can read data
beyond the end of buffer. Sanity-check the directory entry length before
using it.

Reported-and-tested-by: syzbot+6fc7fb214625d82af7d1@syzkaller.appspotmail.com
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c
index 350f67fb5b9c0..41ece64f1a340 100644
--- a/fs/isofs/inode.c
+++ b/fs/isofs/inode.c
@@ -1268,6 +1268,8 @@ static int isofs_read_inode(struct inode *inode, int relocated)
 
 	de = (struct iso_directory_record *) (bh->b_data + offset);
 	de_len = *(unsigned char *) de;
+	if (de_len < sizeof(struct iso_directory_record))
+		goto fail;
 
 	if (offset + de_len > bufsize) {
 		int frag1 = bufsize - offset;