Correctly handle potential buffer malloc() failure in HIOMAP write window request

kestrel/src/ipmi_bt.h

@@ -72,6 +72,7 @@
 #define IPMI_CC_NO_ERROR        0x00
 #define IPMI_CC_SNS_NOT_PRSNT   0xcb
 #define IPMI_CC_INVALID_COMMAND 0xc1
+#define IPMI_CC_OUT_OF_SPACE    0xc4
 
 #define BASE_IPMI_REQUEST_LENGTH    3
 #define BASE_IPMI_RESPONSE_LENGTH   4

kestrel/src/kestrel.c

@@ -1544,6 +1544,13 @@ static int process_host_to_bmc_ipmi_bt_transactions(void)
                                             hiomap_config.write_windows[hiomap_config.write_window_count].start_address = hiomap_config.window_start_address;
                                             hiomap_config.write_windows[hiomap_config.write_window_count].bytes = hiomap_config.window_length_bytes;
                                             hiomap_config.write_windows[hiomap_config.write_window_count].buffer = malloc(FLASH_MAX_WR_WINDOW_BYTES);
+                                            if (hiomap_config.write_windows[hiomap_config.write_window_count].buffer == NULL)
+                                            {
+                                                KESTREL_LOG("[ERROR] Unable to allocate HIOMAP buffer space!\n");
+                                                response.length = BASE_IPMI_RESPONSE_LENGTH;
+                                                response.completion_code = IPMI_CC_OUT_OF_SPACE;
+                                                break;
+                                            }
                                             hiomap_config.write_windows[hiomap_config.write_window_count].active = 1;
                                             hiomap_write_buffer = hiomap_config.write_windows[hiomap_config.write_window_count].buffer;
                                             hiomap_config.write_window_count++;