coverity: Dereferencing a null pointer in lib/dns/tests/rbt_test.c

** CID 1430161:    (NULL_RETURNS)
/lib/dns/tests/rbt_test.c: 1142 in atfu_rbt_addname_body()
/lib/dns/tests/rbt_test.c: 1153 in atfu_rbt_addname_body()


________________________________________________________________________________________________________
*** CID 1430161:    (NULL_RETURNS)
/lib/dns/tests/rbt_test.c: 1142 in atfu_rbt_addname_body()
1136            result = dns_test_begin(NULL, ISC_TRUE);
1137            ATF_CHECK_EQ(result, ISC_R_SUCCESS);
1138
1139            ctx = test_context_setup();
1140
1141            n = isc_mem_get(mctx, sizeof(size_t));
>>>     CID 1430161:    (NULL_RETURNS)
>>>     Dereferencing a null pointer "n".
1142            *n = 1;
1143
1144            dns_test_namefromstring("d.e.f.g.h.i.j.k", &fname);
1145            name = dns_fixedname_name(&fname);
1146
1147            /* Add a name that doesn't exist */
/lib/dns/tests/rbt_test.c: 1153 in atfu_rbt_addname_body()
1147            /* Add a name that doesn't exist */
1148            result = dns_rbt_addname(ctx->rbt, name, n);
1149            ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
1150
1151            /* Now add again, should get ISC_R_EXISTS */
1152            n = isc_mem_get(mctx, sizeof(size_t));
>>>     CID 1430161:    (NULL_RETURNS)
>>>     Dereferencing a null pointer "n".
1153            *n = 2;
1154            result = dns_rbt_addname(ctx->rbt, name, n);
1155            ATF_REQUIRE_EQ(result, ISC_R_EXISTS);
1156            isc_mem_put(mctx, n, sizeof(size_t));
1157
1158            test_context_teardown(ctx);