linux-kernel - [PATCH 4.14 14/22] isofs: Fix out of bound access for corrupted isofs image

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Date:   Wed, 10 Nov 2021 19:43:34 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jan Kara <jack@...e.cz>,
        syzbot+6fc7fb214625d82af7d1@...kaller.appspotmail.com
Subject: [PATCH 4.14 14/22] isofs: Fix out of bound access for corrupted isofs image

From: Jan Kara <jack@...e.cz>

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@...kaller.appspotmail.com
CC: stable@...r.kernel.org
Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/isofs/inode.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/isofs/inode.c
+++ b/fs/isofs/inode.c
@@ -1326,6 +1326,8 @@ static int isofs_read_inode(struct inode
 
 	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;