[PATCH v2 05/10] cmdline: fix port list parsing

[David Marchand <david.marchand@redhat.com>]

Doing arithmetics with the NULL pointer is undefined.

Caught by UBSan:

../lib/cmdline/cmdline_parse_portlist.c:40:19: runtime error:
	applying non-zero offset 1 to null pointer
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
	../lib/cmdline/cmdline_parse_portlist.c:40:19 in

Fixes: af75078fece3 ("first public release")
Cc: stable@dpdk.org

Signed-off-by: David Marchand <david.marchand@redhat.com>
---
Changes since v1:
- moved some variable as suggested by Bruce,

---
 lib/cmdline/cmdline_parse_portlist.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/cmdline/cmdline_parse_portlist.c b/lib/cmdline/cmdline_parse_portlist.c
index ef6ce223b5..549f6d9671 100644
--- a/lib/cmdline/cmdline_parse_portlist.c
+++ b/lib/cmdline/cmdline_parse_portlist.c
@@ -33,15 +33,12 @@ parse_set_list(cmdline_portlist_t *pl, size_t low, size_t high)
 static int
 parse_ports(cmdline_portlist_t *pl, const char *str)
 {
+	const char *first = str;
 	size_t ps, pe;
-	const char *first, *last;
 	char *end;
 
-	for (first = str, last = first;
-	    first != NULL && last != NULL;
-	    first = last + 1) {
-
-		last = strchr(first, ',');
+	while (first != NULL) {
+		const char *last = strchr(first, ',');
 
 		errno = 0;
 		ps = strtoul(first, &end, 10);
@@ -65,6 +62,7 @@ parse_ports(cmdline_portlist_t *pl, const char *str)
 			return -1;
 
 		parse_set_list(pl, ps, pe);
+		first = (last == NULL ? NULL : last + 1);
 	}
 
 	return 0;
-- 
2.49.0