Squashed commit upgrading to mbedtls-2.27.0

Squash merging branch import/mbedtls-2.27.0

 335b95f50f90 ("core: libmbedtls: add ctr_drbg.c to core sources")
 9ad9df8b36e4 ("core: libtomcrypt: libmbedtls: mbedtls_mpi_montred() now returns void")
 ade0994c57b3 ("libmbedtls: add SM2 curve")
 3041cf9726e2 ("libmbedtls: mbedtls_mpi_exp_mod(): optimize mempool usage")
 a2e7a4cd262d ("libmbedtls: mbedtls_mpi_exp_mod(): reduce stack usage")
 87efbd27f8e0 ("libmbedtls: mbedtls_mpi_exp_mod() initialize W")
 e7c59b9b1d5f ("libmbedtls: fix no CRT issue")
 d76bd278d9e2 ("libmbedtls: add interfaces in mbedtls for context memory operation")
 e5b6c167f809 ("libmedtls: mpi_miller_rabin: increase count limit")
 b81d896a903d ("libmbedtls: add mbedtls_mpi_init_mempool()")
 3fbd8660c09d ("libmbedtls: make mbedtls_mpi_mont*() available")
 2cc759c67e37 ("mbedtls: configure mbedtls to reach for config")
 48bf81758c6e ("mbedtls: remove default include/mbedtls/config.h")
 3602df84d7b3 ("Import mbedtls-2.27.0")

Signed-off-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/ecdsa.c b/lib/libmbedtls/mbedtls/library/ecdsa.c
index bf99573..640eb24 100644
--- a/lib/libmbedtls/mbedtls/library/ecdsa.c
+++ b/lib/libmbedtls/mbedtls/library/ecdsa.c
@@ -1,8 +1,8 @@
-// SPDX-License-Identifier: Apache-2.0
 /*
  *  Elliptic curve DSA
  *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
  *  not use this file except in compliance with the License.
@@ -15,8 +15,6 @@
  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 
 /*
@@ -25,11 +23,7 @@
  * SEC1 http://www.secg.org/index.php?action=secg,docs_secg
  */
 
-#if !defined(MBEDTLS_CONFIG_FILE)
-#include "mbedtls/config.h"
-#else
-#include MBEDTLS_CONFIG_FILE
-#endif
+#include "common.h"
 
 #if defined(MBEDTLS_ECDSA_C)
 
@@ -223,6 +217,9 @@
 
 #endif /* MBEDTLS_ECP_RESTARTABLE */
 
+#if defined(MBEDTLS_ECDSA_DETERMINISTIC) || \
+    !defined(MBEDTLS_ECDSA_SIGN_ALT)     || \
+    !defined(MBEDTLS_ECDSA_VERIFY_ALT)
 /*
  * Derive a suitable integer for group grp from a buffer of length len
  * SEC1 4.1.3 step 5 aka SEC1 4.1.4 step 3
@@ -245,6 +242,7 @@
 cleanup:
     return( ret );
 }
+#endif /* ECDSA_DETERMINISTIC || !ECDSA_SIGN_ALT || !ECDSA_VERIFY_ALT */
 
 #if !defined(MBEDTLS_ECDSA_SIGN_ALT)
 /*
@@ -472,6 +470,8 @@
 sign:
 #endif
 #if defined(MBEDTLS_ECDSA_SIGN_ALT)
+    (void) f_rng_blind;
+    (void) p_rng_blind;
     ret = mbedtls_ecdsa_sign( grp, r, s, d, buf, blen,
                               mbedtls_hmac_drbg_random, p_rng );
 #else
@@ -726,7 +726,7 @@
                                     unsigned char *sig, size_t *slen )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
-    unsigned char buf[MBEDTLS_ECDSA_MAX_LEN];
+    unsigned char buf[MBEDTLS_ECDSA_MAX_LEN] = {0};
     unsigned char *p = buf + sizeof( buf );
     size_t len = 0;
 
@@ -772,6 +772,8 @@
     (void) md_alg;
 
 #if defined(MBEDTLS_ECDSA_SIGN_ALT)
+    (void) rs_ctx;
+
     MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ctx->grp, &r, &s, &ctx->d,
                          hash, hlen, f_rng, p_rng ) );
 #else
@@ -868,8 +870,8 @@
 
     if( p + len != end )
     {
-        ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA +
-              MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
+              MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
         goto cleanup;
     }
 
@@ -880,6 +882,8 @@
         goto cleanup;
     }
 #if defined(MBEDTLS_ECDSA_VERIFY_ALT)
+    (void) rs_ctx;
+
     if( ( ret = mbedtls_ecdsa_verify( &ctx->grp, hash, hlen,
                                       &ctx->Q, &r, &s ) ) != 0 )
         goto cleanup;