s390/boot: Bound command line facility ranges

The facilities and debug-alternative command line parsers iterate over
inclusive numeric ranges. If a range ends at ULONG_MAX, incrementing the
current value wraps to zero and the loop never terminates. Large finite
out-of-range values also cause unnecessary early boot iterations even
though the bitmap helpers ignore them.

Stop each loop at the size of the bitmap it modifies. This preserves all
meaningful range values while guaranteeing termination.

Reviewed-by: Heiko Carstens <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>
Signed-off-by: Heiko Carstens <[email protected]>

arch/s390/boot/alternative.c

@@ -45,11 +45,12 @@ static void alt_debug_modify(int type, unsigned int nr, bool clear)
 
 static char *alt_debug_parse(int type, char *str)
 {
-	unsigned long val, endval;
+	unsigned long val, endval, limit;
 	char *endp;
 	bool clear;
 	int i;
 
+	limit = type == ALT_TYPE_FACILITY ? MAX_FACILITY_BIT : MAX_MFEATURE_BIT;
 	if (*str == ':') {
 		str++;
 	} else {
@@ -73,7 +74,7 @@ static char *alt_debug_parse(int type, char *str)
 			if (str == endp)
 				break;
 			str = endp;
-			while (val <= endval) {
+			while (val <= endval && val < limit) {
 				alt_debug_modify(type, val, clear);
 				val++;
 			}

arch/s390/boot/ipl_parm.c

@@ -230,7 +230,7 @@ static void modify_fac_list(char *str)
 			if (str == endp)
 				break;
 			str = endp;
-			while (val <= endval) {
+			while (val <= endval && val < MAX_FACILITY_BIT) {
 				modify_facility(val, clear);
 				val++;
 			}