nss-myhostname: use INC_SAFE for buffer index accumulation

Use overflow-safe INC_SAFE() instead of raw addition for idx
accumulation, so that Coverity can see the addition is checked.

CID#1548028

Follow-up for a05483a921a518fd283e7cb32dc8c8e816b2ab2c

diff --git a/src/nss-myhostname/nss-myhostname.c b/src/nss-myhostname/nss-myhostname.c
index 6a016a1f5cc12c6a51d87ff330a633fb5e08a0dc..601a4198dd8e8a241f4f27802e68c7e1397bbfbc 100644 (file)
--- a/src/nss-myhostname/nss-myhostname.c
+++ b/src/nss-myhostname/nss-myhostname.c
@@ -238,14 +238,10 @@ static enum nss_status fill_in_hostent(
         if (additional) {
                 ((char**) r_aliases)[0] = r_alias;
                 ((char**) r_aliases)[1] = NULL;
-                /* Silence static analyzers */
-                assert(idx <= buflen - 2 * sizeof(char*));
-                idx += 2*sizeof(char*);
+                assert_se(INC_SAFE(&idx, 2 * sizeof(char*)));
         } else {
                 ((char**) r_aliases)[0] = NULL;
-                /* Silence static analyzers */
-                assert(idx <= buflen - sizeof(char*));
-                idx += sizeof(char*);
+                assert_se(INC_SAFE(&idx, sizeof(char*)));
         }
 
         /* Third, add addresses */