drivers/cdrom/cdrom.c: relax check on dvd manufacturer value

The report has an ISO which has a very long manufacturer ID. It seems
that Linux is wrong, not the ISO maker.

Relax the check for the length of this field: emit a warning and truncate
the incoming data to 2048 bytes rather than rejecting the entire thing.

dvd_manufact.value isn't null-terminated. I'm not even sure if it's a
string. The kernel doesn't apepar to use it anyway.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=39062

Reported-by: <[e-mail]>
Tested-by: <[e-mail]>
Cc: Jens Axboe <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/cdrom/cdrom.c

···
 		goto out;
 
 	s->manufact.len = buf[0] << 8 | buf[1];
-	if (s->manufact.len < 0 || s->manufact.len > 2048) {
+	if (s->manufact.len < 0) {
 		cdinfo(CD_WARNING, "Received invalid manufacture info length"
 				   " (%d)\n", s->manufact.len);
 		ret = -EIO;
 	} else {
+		if (s->manufact.len > 2048) {
+			cdinfo(CD_WARNING, "Received invalid manufacture info "
+					"length (%d): truncating to 2048\n",
+					s->manufact.len);
+			s->manufact.len = 2048;
+		}
 		memcpy(s->manufact.value, &buf[4], s->manufact.len);
 	}