esp_http_client example: fix potential buffer overflow while copying data recieved in HTTP response

Closes https://github.com/espressif/esp-idf/issues/10436

examples/protocols/esp_http_client/main/esp_http_client_example.c

@@ -8,6 +8,7 @@
 */
 
 #include <string.h>
+#include <sys/param.h>
 #include <stdlib.h>
 #include "esp_log.h"
 #include "nvs_flash.h"
@@ -73,20 +74,28 @@ esp_err_t _http_event_handler(esp_http_client_event_t *evt)
              */
             if (!esp_http_client_is_chunked_response(evt->client)) {
                 // If user_data buffer is configured, copy the response into the buffer
+                int copy_len = 0;
                 if (evt->user_data) {
-                    memcpy(evt->user_data + output_len, evt->data, evt->data_len);
+                    copy_len = MIN(evt->data_len, (MAX_HTTP_OUTPUT_BUFFER - output_len));
+                    if (copy_len) {
+                        memcpy(evt->user_data + output_len, evt->data, copy_len);
+                    }
                 } else {
+                    const int buffer_len = esp_http_client_get_content_length(evt->client);
                     if (output_buffer == NULL) {
-                        output_buffer = (char *) malloc(esp_http_client_get_content_length(evt->client));
+                        output_buffer = (char *) malloc(buffer_len);
                         output_len = 0;
                         if (output_buffer == NULL) {
                             ESP_LOGE(TAG, "Failed to allocate memory for output buffer");
                             return ESP_FAIL;
                         }
                     }
-                    memcpy(output_buffer + output_len, evt->data, evt->data_len);
+                    copy_len = MIN(evt->data_len, (buffer_len - output_len));
+                    if (copy_len) {
+                        memcpy(output_buffer + output_len, evt->data, copy_len);
+                    }
                 }
-                output_len += evt->data_len;
+                output_len += copy_len;
             }
 
             break;