[PATCH 4.19 08/16] isofs: Fix out of bound access for corrupted isofs image

[Greg Kroah-Hartman]

From: Jan Kara <jack@xxxxxxx>

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@xxxxxxxxxxxxxxxxxxxxxxxxx
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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;