diff --git a/include/psa/crypto_builtin_composites.h b/include/psa/crypto_builtin_composites.h
index 7122cc8..ba3d253 100644
--- a/include/psa/crypto_builtin_composites.h
+++ b/include/psa/crypto_builtin_composites.h
@@ -120,7 +120,7 @@
     size_t MBEDTLS_PRIVATE(coordinate_bytes);
     psa_algorithm_t MBEDTLS_PRIVATE(alg);
     mbedtls_md_type_t MBEDTLS_PRIVATE(md_alg);
-    const uint8_t *MBEDTLS_PRIVATE(hash);
+    uint8_t *MBEDTLS_PRIVATE(hash);
     size_t MBEDTLS_PRIVATE(hash_length);
 
 #else
@@ -150,7 +150,7 @@
     mbedtls_ecdsa_context *MBEDTLS_PRIVATE(ctx);
     mbedtls_ecdsa_restart_ctx MBEDTLS_PRIVATE(restart_ctx);
 
-    const uint8_t *MBEDTLS_PRIVATE(hash);
+    uint8_t *MBEDTLS_PRIVATE(hash);
     size_t MBEDTLS_PRIVATE(hash_length);
 
     mbedtls_mpi MBEDTLS_PRIVATE(r);
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 93b4045..a3bc806 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -3516,7 +3516,13 @@
     operation->md_alg = mbedtls_hash_info_md_from_psa(hash_alg);
     operation->alg = alg;
 
-    operation->hash = hash;
+    operation->hash = mbedtls_calloc(1, hash_length);
+
+    if (operation->hash == NULL) {
+        return PSA_ERROR_INSUFFICIENT_MEMORY;
+    }
+
+    memcpy(operation->hash, hash, hash_length);
     operation->hash_length = hash_length;
 
     return PSA_SUCCESS;
@@ -3643,8 +3649,12 @@
     if (operation->ctx) {
         mbedtls_ecdsa_free(operation->ctx);
         mbedtls_free(operation->ctx);
+        operation->ctx = NULL;
     }
 
+    mbedtls_free(operation->hash);
+    operation->hash = NULL;
+
     mbedtls_ecdsa_restart_free(&operation->restart_ctx);
 
     return PSA_SUCCESS;
@@ -3743,7 +3753,13 @@
 
     mbedtls_ecdsa_restart_init(&operation->restart_ctx);
 
-    operation->hash = hash;
+    operation->hash = mbedtls_calloc(1, hash_length);
+
+    if (operation->hash == NULL) {
+        return PSA_ERROR_INSUFFICIENT_MEMORY;
+    }
+
+    memcpy(operation->hash, hash, hash_length);
     operation->hash_length = hash_length;
 
     return PSA_SUCCESS;
@@ -3802,8 +3818,12 @@
     if (operation->ctx) {
         mbedtls_ecdsa_free(operation->ctx);
         mbedtls_free(operation->ctx);
+        operation->ctx = NULL;
     }
 
+    mbedtls_free(operation->hash);
+    operation->hash = NULL;
+
     mbedtls_ecdsa_restart_free(&operation->restart_ctx);
 
     mbedtls_mpi_free(&operation->r);
diff --git a/library/psa_crypto_core.h b/library/psa_crypto_core.h
index 610d780..f74db70 100644
--- a/library/psa_crypto_core.h
+++ b/library/psa_crypto_core.h
@@ -711,7 +711,8 @@
  * \retval #PSA_ERROR_NOT_SUPPORTED Either no internal interruptible operations
  *         are currently supported, or the key type is currently unsupported.
  * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
- *         There was insufficient memory to load the key representation.
+ *         There was insufficient memory either to load the key representation,
+ *         or to store the hash.
  */
 psa_status_t mbedtls_psa_sign_hash_start(
     mbedtls_psa_sign_hash_interruptible_operation_t *operation,
@@ -815,7 +816,8 @@
  *        Either no internal interruptible operations are currently supported,
  *         or the key type is currently unsupported.
  * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
- *        There was insufficient memory to load the key representation.
+ *        There was insufficient memory either to load the key representation,
+ *        or to store the hash.
  */
 psa_status_t mbedtls_psa_verify_hash_start(
     mbedtls_psa_verify_hash_interruptible_operation_t *operation,
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index 7b9daae..f050abf 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -7174,6 +7174,7 @@
     size_t signature_size;
     size_t signature_length = 0xdeadbeef;
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+    uint8_t *input_buffer = NULL;
     psa_sign_hash_interruptible_operation_t sign_operation =
         psa_sign_hash_interruptible_operation_init();
     psa_verify_hash_interruptible_operation_t verify_operation =
@@ -7351,6 +7352,45 @@
 
     PSA_ASSERT(psa_sign_hash_abort(&sign_operation));
 
+    /* Trash the hash buffer in between start and complete, to ensure
+     * no reliance on external buffers. */
+    psa_interruptible_set_max_ops(PSA_INTERRUPTIBLE_MAX_OPS_UNLIMITED);
+
+    input_buffer = mbedtls_calloc(1, input_data->len);
+    TEST_ASSERT(input_buffer != NULL);
+
+    memcpy(input_buffer, input_data->x, input_data->len);
+
+    PSA_ASSERT(psa_sign_hash_start(&sign_operation, key, alg,
+                                   input_buffer, input_data->len));
+
+    memset(input_buffer, '!', input_data->len);
+    mbedtls_free(input_buffer);
+    input_buffer = NULL;
+
+    PSA_ASSERT(psa_sign_hash_complete(&sign_operation, signature,
+                                      signature_size,
+                                      &signature_length));
+
+    PSA_ASSERT(psa_sign_hash_abort(&sign_operation));
+
+    input_buffer = mbedtls_calloc(1, input_data->len);
+    TEST_ASSERT(input_buffer != NULL);
+
+    memcpy(input_buffer, input_data->x, input_data->len);
+
+    PSA_ASSERT(psa_verify_hash_start(&verify_operation, key, alg,
+                                     input_buffer, input_data->len,
+                                     signature, signature_length));
+
+    memset(input_buffer, '!', input_data->len);
+    mbedtls_free(input_buffer);
+    input_buffer = NULL;
+
+    PSA_ASSERT(psa_verify_hash_complete(&verify_operation));
+
+    PSA_ASSERT(psa_verify_hash_abort(&verify_operation));
+
 exit:
     /*
      * Key attributes may have been returned by psa_get_key_attributes()