Error reading coredump from flash in ESP32-S3

[iParcelBox]

I have an ESP32-S3 with secure boot and encryption enabled. I'm saving coredump data to flash.

If I manually call abort() within the code, once the device has rebooted I can call a command to read the cordump partition to UART, which works successfully and I can see that the base64 encoded core dump starts with:

f0VMRgEBAQAAAAAAAAAAAAQAXgABAAAAAAAAADQAAAAAAAAAAAAAADQAIAAsACgAAAAAAAQAAAC0BQAAAAAAAAAAAADgMQAA4DEAAAYAAAAAAAAAAQAAAJQ3AADYycw/2MnMP1wBAABcAQAABgAAAAAAAAABAAAA8DgAALBaGzywWhs8QAMAAEADAAAGAAAAAAAAAAEAAAAwPAAA+GjLP/hoyz9cAQAAXAEAAAYAAAAAAAAAAQAAAIw9AAAAZss/AGbLP6ACAACgAgAABgAAAAAAAAABAAAALEAAAPBwyz/wcMs/XAEAAFwBAAAGAAAAAAAAAAEAAACIQQAAAG7LPwBuyz+gAgAAoAIAAAYAAAAAAAAAAQAAAChEAAAwI84/MCPOP1wBAABcAQAABgAAAAAAAAABAAAAhEUAAIBsGjyAbBo80AMAANADAAAGAAAAAAAAAAEAAABUSQAAxDDMP8QwzD9cAQAAXAEAAAYAAAAAAAAAAQAAALBKAACgK8w/oCvMPxADAAAQAwAABgAAAAAAAAABAAAAwE0AAFyYzD9cmMw/XAEAAFwBAAAGAAAAAAAAAAEAAAAcTwAAcJTMP3CUzD/gAgAA

However, if the firmware crashes for some other reason (e.g. Heap Memory poisoning) and after rebooting I then call the same command to read the coredump partition, I get a very different looking response, starting as follows:

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

Note that currently I'm trimming the first 24 bytes of the partition data, so that when working correctly, the decoded data starts with \x7fELF

Here is the function I'm using to read the coredump data from the partition:

Code: Select all

// Find the coredump partition
    const esp_partition_t *core_dump_partition = esp_partition_find_first(
        ESP_PARTITION_TYPE_DATA, ESP_PARTITION_SUBTYPE_DATA_COREDUMP, "coredump");

    if (!core_dump_partition)
    {
        ESP_LOGE(TAG, "Core dump partition not found!");
        args->result = ipb_strdup("Core dump partition not found!"); // freed in calling function
        xSemaphoreGive(args->semaphore);
        vTaskDelete(NULL);
    }

    ESP_LOGI(TAG, "Core dump partition: %s, size: %ld", core_dump_partition->label, core_dump_partition->size);

    // Read the core dump size
    size_t core_dump_size = core_dump_partition->size;
    uint8_t *core_dump_data = malloc(core_dump_size + 1);
    if (!core_dump_data)
    {
        ESP_LOGE(TAG, "Failed to allocate memory for core dump");
        args->result = NULL;
        xSemaphoreGive(args->semaphore);
        vTaskDelete(NULL);
    }

    esp_err_t err = esp_partition_read(core_dump_partition, 0, core_dump_data, core_dump_size);
    if (err != ESP_OK)
    {
        ESP_LOGE(TAG, "Failed to read core dump data: %s", esp_err_to_name(err));
        free(core_dump_data);
        args->result = ipb_strdup("Failed to read core dump data"); // freed in calling function
        xSemaphoreGive(args->semaphore);
        vTaskDelete(NULL);
    }

    // Trim the first 20 bytes
    uint8_t *trimmed_core_dump_data = core_dump_data + 24;
    size_t trimmed_core_dump_size = core_dump_size - 24;

    // Calculate Base64 encoded size
    size_t encoded_size = 0;
    mbedtls_base64_encode(NULL, 0, &encoded_size, trimmed_core_dump_data, trimmed_core_dump_size);
    uint8_t *encoded_data = malloc(encoded_size + 1); // used as return, so freed in calling function
    if (!encoded_data)
    {
        ESP_LOGE(TAG, "Failed to allocate memory for encoded data");
        free(core_dump_data); // Free original buffer
        args->result = NULL;
        xSemaphoreGive(args->semaphore);
        vTaskDelete(NULL);
    }

    // Encode core dump to Base64
    err = mbedtls_base64_encode(encoded_data, encoded_size, &encoded_size, trimmed_core_dump_data, trimmed_core_dump_size);
    if (err != 0)
    {
        ESP_LOGE(TAG, "Failed to encode core dump data to Base64");
        free(core_dump_data); // Free original buffer
        free(encoded_data);   // Free allocated memory
        args->result = NULL;
        xSemaphoreGive(args->semaphore);
        vTaskDelete(NULL);
    }

    encoded_data[encoded_size] = '\0'; // Null-terminate the Base64 string
    ESP_LOGI(TAG, "Core dump encoded size: %d", encoded_size);

    // Debug logs for verification
    ESP_LOGI(TAG, "Encoded core dump: %.16s", encoded_data);

    // Clean up and set the result
    free(core_dump_data); // Free original buffer
    args->result = (char *)encoded_data;

    // Signal task completion
    xSemaphoreGive(args->semaphore);
    

Is this a bug?

[iParcelBox]

For others encountering similar problems, it turns out because I had ESP Insights enabled, it was deleting the coredump partition after transmitting coredump summary info to the dashboard. More details and some code examples at https://github.com/espressif/esp-idf/issues/15221