core: fix possible crash in g_utf8_validate()

We can skip additional UTF-8 validity check when parsing operator.
mm_charset_take_and_convert_to_utf8() already does a UTF-8 validity check
internally before returning the string, so it's pointless to do a new one
on the returned string.
Plus, mm_charset_take_and_convert_to_utf8() may really return NULL, which
would end up in segfaulting as g_utf8_validate() expects always a non-NULL
string.

Based on 219424a6e2d017491a05ecbed661bccde3f991ef (MM_06 branch)

1 files changed, 5 insertions, 4 deletions

diff --git a/src/mm-modem-helpers.c b/src/mm-modem-helpers.c
index 8cf9a29f..928fa6f3 100644
--- a/src/mm-modem-helpers.c
+++ b/src/mm-modem-helpers.c
@@ -1511,13 +1511,14 @@ mm_3gpp_parse_operator (const gchar *reply,
          * string of the bytes of the operator name as encoded by the current
          * character set.
          */
-        if (cur_charset == MM_MODEM_CHARSET_UCS2)
+        if (cur_charset == MM_MODEM_CHARSET_UCS2) {
+            /* In this case we're already checking UTF-8 validity */
             operator = mm_charset_take_and_convert_to_utf8 (operator, MM_MODEM_CHARSET_UCS2);
-
+        }
         /* Ensure the operator name is valid UTF-8 so that we can send it
          * through D-Bus and such.
          */
-        if (!g_utf8_validate (operator, -1, NULL)) {
+        else if (!g_utf8_validate (operator, -1, NULL)) {
             g_free (operator);
             return NULL;
         }
@@ -1525,7 +1526,7 @@ mm_3gpp_parse_operator (const gchar *reply,
         /* Some modems (Novatel LTE) return the operator name as "Unknown" when
          * it fails to obtain the operator name. Return NULL in such case.
          */
-        if (g_ascii_strcasecmp (operator, "unknown") == 0) {
+        if (operator && g_ascii_strcasecmp (operator, "unknown") == 0) {
             g_free (operator);
             return NULL;
         }