MFC 198820:

Ensure 'kvm' is always initialized.  If "-M" was not specified and the
garbage value on the stack was not zero, then 'ddb capture' would try to
use the garbage value as a kvm_t pointer.

sbin/ddb/ddb_capture.c

@@ -204,6 +204,7 @@ ddb_capture(int argc, char *argv[])
 
 	mflag = NULL;
 	nflag = NULL;
+	kvm = NULL;
 	while ((ch = getopt(argc, argv, "M:N:")) != -1) {
 		switch (ch) {
 		case 'M':