From 07465563c55d9f542261f76cebb64c6705a7156e Mon Sep 17 00:00:00 2001
From: Angus Gratton <angus@espressif.com>
Date: Thu, 8 Jul 2021 19:07:42 +1000
Subject: [PATCH] secure boot: Fix incorrect handling of
 mbedtls_ctr_drbg_seed() failure in signature verification

Increase the test app optimization level to one that would find this issue.
---
 .../src/secure_boot_v2/secure_boot_signatures_app.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/components/bootloader_support/src/secure_boot_v2/secure_boot_signatures_app.c b/components/bootloader_support/src/secure_boot_v2/secure_boot_signatures_app.c
index 6fecadc251..a30827b2fc 100644
--- a/components/bootloader_support/src/secure_boot_v2/secure_boot_signatures_app.c
+++ b/components/bootloader_support/src/secure_boot_v2/secure_boot_signatures_app.c
@@ -195,7 +195,7 @@ esp_err_t esp_secure_boot_verify_rsa_signature_block(const ets_secure_boot_signa
     ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, NULL, 0);
     if (ret != 0) {
         ESP_LOGE(TAG, "mbedtls_ctr_drbg_seed returned -0x%04x\n", ret);
-        goto exit;
+        goto exit_outer;
     }
 
 #ifdef CONFIG_SECURE_SIGNED_ON_UPDATE_NO_SECURE_BOOT
@@ -247,19 +247,19 @@ esp_err_t esp_secure_boot_verify_rsa_signature_block(const ets_secure_boot_signa
         ret = mbedtls_rsa_import(&pk, &N, NULL, NULL, NULL, &e);
         if (ret != 0) {
             ESP_LOGE(TAG, "Failed mbedtls_rsa_import, err: %d", ret);
-            goto exit;
+            goto exit_inner;
         }
 
         ret = mbedtls_rsa_complete(&pk);
         if (ret != 0) {
             ESP_LOGE(TAG, "Failed mbedtls_rsa_complete, err: %d", ret);
-            goto exit;
+            goto exit_inner;
         }
 
         ret = mbedtls_rsa_check_pubkey(&pk);
         if (ret != 0) {
             ESP_LOGI(TAG, "Key is not an RSA key -%0x", -ret);
-            goto exit;
+            goto exit_inner;
         }
 
         /* Signature needs to be byte swapped into BE representation */
@@ -270,7 +270,7 @@ esp_err_t esp_secure_boot_verify_rsa_signature_block(const ets_secure_boot_signa
         ret = mbedtls_rsa_public( &pk, sig_be, buf);
         if (ret != 0) {
             ESP_LOGE(TAG, "mbedtls_rsa_public failed, err: %d", ret);
-            goto exit;
+            goto exit_inner;
         }
 
         ret = mbedtls_rsa_rsassa_pss_verify( &pk, mbedtls_ctr_drbg_random, &ctr_drbg, MBEDTLS_RSA_PUBLIC, MBEDTLS_MD_SHA256, ESP_SECURE_BOOT_DIGEST_LEN,
@@ -280,13 +280,14 @@ esp_err_t esp_secure_boot_verify_rsa_signature_block(const ets_secure_boot_signa
         } else {
             ESP_LOGI(TAG, "Signature verified successfully!");
         }
-exit:
+exit_inner:
         mbedtls_rsa_free(&pk);
         if (ret == 0) {
             break;
         }
     }
 
+ exit_outer:
     free(sig_be);
     free(buf);
     return (ret != 0 || any_trusted_key == false) ? ESP_ERR_IMAGE_INVALID: ESP_OK;