Sanity check the list obtained from the kern.disks sysctl so that Disk_Names()

doesn't get fooled into returning a bogus list.  This should fix sysinstall
from segfaulting when no disk devices are present.

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/libdisk/disk.c b/lib/libdisk/disk.c
index c750c2b..ae79d29 100644
--- a/lib/libdisk/disk.c
+++ b/lib/libdisk/disk.c
@@ -470,6 +470,9 @@ Disk_Names()
 		return NULL;
 	}
 
+	if (listsize == 0)
+		return (NULL);
+
 	disks = malloc(sizeof *disks * (1 + MAX_NO_DISKS));
 	if (disks == NULL)
 		return NULL;
@@ -481,7 +484,7 @@ Disk_Names()
 	memset(disks,0,sizeof *disks * (1 + MAX_NO_DISKS));
 	memset(disklist, 0, listsize + 1);
 	error = sysctlbyname("kern.disks", disklist, &listsize, NULL, 0);
-	if (error) {
+	if (error || disklist[0] == 0) {
 		free(disklist);
 		free(disks);
 		return NULL;