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

[David Marchand]

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: sta...@dpdk.org

Signed-off-by: David Marchand <david.march...@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