commit 43f636ff4d23f0c5a07ca961d1b6e6307c8f17ed
author Gilles Peskine <gilles.peskine@arm.com> Tue Mar 11 17:38:28 2025 +0100
committer GitHub <noreply@github.com> Tue Mar 11 17:38:28 2025 +0100
tree e6cb3052db2892a1d19ebb90579e80d0b92dc9d1
parent 9a9f0c77cfd314b761aaeef7a521565e00019b4a
parent ce726b23fa70816f77832cdc1883b3796efe0687

Merge pull request #1316 from gilles-peskine-arm/zeroize-psa-202503-3.6

Backport 3.6: Zeroize PSA temporary heap buffers

ChangeLog.d/psa-zeroize.txt

diff --git a/ChangeLog.d/psa-zeroize.txt b/ChangeLog.d/psa-zeroize.txt
new file mode 100644
index 0000000..6bdaa00
--- /dev/null
+++ b/ChangeLog.d/psa-zeroize.txt
@@ -0,0 +1,4 @@
+Security
+   * Zeroize a temporary heap buffer used in psa_key_derivation_output_key()
+     when deriving an ECC key pair.
+   * Zeroize temporary heap buffers used in PSA operations.

library/psa_crypto.c

diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index b576f95..4ccb75b 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -6316,7 +6316,7 @@
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     size_t m;
-    size_t m_bytes;
+    size_t m_bytes = 0;
 
     mbedtls_mpi_init(&k);
     mbedtls_mpi_init(&diff_N_2);
@@ -6389,7 +6389,7 @@
         status = mbedtls_to_psa_error(ret);
     }
     if (status != PSA_SUCCESS) {
-        mbedtls_free(*data);
+        mbedtls_zeroize_and_free(*data, m_bytes);
         *data = NULL;
     }
     mbedtls_mpi_free(&k);
@@ -6564,7 +6564,7 @@
     }
 
 exit:
-    mbedtls_free(data);
+    mbedtls_zeroize_and_free(data, bytes);
     return status;
 }
 
@@ -9300,7 +9300,7 @@
     return PSA_SUCCESS;
 
 error:
-    mbedtls_free(local_input->buffer);
+    mbedtls_zeroize_and_free(local_input->buffer, local_input->length);
     local_input->buffer = NULL;
     local_input->length = 0;
     return status;
@@ -9308,7 +9308,7 @@
 
 void psa_crypto_local_input_free(psa_crypto_local_input_t *local_input)
 {
-    mbedtls_free(local_input->buffer);
+    mbedtls_zeroize_and_free(local_input->buffer, local_input->length);
     local_input->buffer = NULL;
     local_input->length = 0;
 }
@@ -9352,7 +9352,7 @@
         return status;
     }
 
-    mbedtls_free(local_output->buffer);
+    mbedtls_zeroize_and_free(local_output->buffer, local_output->length);
     local_output->buffer = NULL;
     local_output->length = 0;