From a3fd276be02c4bcbab97889d80bed057efacb489 Mon Sep 17 00:00:00 2001
From: Toomas Soome <tsoome@FreeBSD.org>
Date: Wed, 7 Nov 2018 21:36:52 +0000
Subject: [PATCH] loader: ptable_open() check for ptable_cd9660read result is
 wrong

The ptable_*read() functions return NULL on read errors (and partition table
closed as an side effect). The ptable_open must check the return value and
act properly.

PR:		232483
Reported by:	lev
Reviewed by:	lev,cem
Differential Revision:	https://reviews.freebsd.org/D17890
---
 stand/common/part.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/stand/common/part.c b/stand/common/part.c
index 56366b62104d..a1fa5e69fde7 100644
--- a/stand/common/part.c
+++ b/stand/common/part.c
@@ -675,10 +675,12 @@ ptable_open(void *dev, uint64_t sectors, uint16_t sectorsize,
 	table->type = PTABLE_NONE;
 	STAILQ_INIT(&table->entries);
 
-	if (ptable_iso9660read(table, dev, dread) != NULL) {
-		if (table->type == PTABLE_ISO9660)
-			goto out;
-	}
+	if (ptable_iso9660read(table, dev, dread) == NULL) {
+		/* Read error. */
+		table = NULL;
+		goto out;
+	} else if (table->type == PTABLE_ISO9660)
+		goto out;
 
 #ifdef LOADER_VTOC8_SUPPORT
 	if (be16dec(buf + offsetof(struct vtoc8, magic)) == VTOC_MAGIC) {