Merge branch 'bugfix/fix_memory_leak_on_http_header_fetch_failure' into 'master'

fix(esp_http_client): free header in case of ESP_ERR_HTTP_FETCH_HEADER

See merge request espressif/esp-idf!40528

Author: mahavirj

components/esp_http_client/esp_http_client.c

@@ -1075,6 +1075,7 @@ esp_err_t esp_http_client_cleanup(esp_http_client_handle_t client)
     _clear_auth_data(client);
     free(client->auth_data);
     free(client->current_header_key);
+    free(client->current_header_value);
     free(client->location);
     free(client->auth_header);
     free(client);

components/esp_http_client/lib/http_utils.c

@@ -68,8 +68,16 @@ char *http_utils_append_string(char **str, const char *new_str, int len)
         }
         if (old_str) {
             old_len = strlen(old_str);
-            old_str = realloc(old_str, old_len + l + 1);
-            ESP_RETURN_ON_FALSE(old_str, NULL, TAG, "Memory exhausted");
+            // old_str should not be reallocated directly, as in case of memory exhaustion,
+            // it will be lost and we will not be able to free it.
+            char *tmp = realloc(old_str, old_len + l + 1);
+            if (tmp == NULL) {
+                free(old_str);
+                old_str = NULL;
+                ESP_RETURN_ON_FALSE(tmp, NULL, TAG, "Memory exhausted");
+            }
+            old_str = tmp;
+            // Ensure the new string is null-terminated
             old_str[old_len + l] = 0;
         } else {
             old_str = calloc(1, l + 1);