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 35675a1..f62b5a5 100644
--- a/fs/isofs/inode.c
+++ b/fs/isofs/inode.c
@@ -1321,6 +1321,8 @@ 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;