From fc820d96e0e4a8e861c65990ba034b39a0cd11d4 Mon Sep 17 00:00:00 2001
From: Paul Elliott <paul.elliott@arm.com>
Date: Fri, 13 Jan 2023 16:29:30 +0000
Subject: [PATCH] Fix IAR warnings

IAR was warning that conditional execution could bypass initialisation of
variables, although those same variables were not used uninitialised. Fix
this along with some other IAR warnings.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
---
 ChangeLog.d/fix-iar-warnings.txt | 2 +-
 library/bignum.c                 | 2 +-
 library/ecp.c                    | 8 +++++---
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/ChangeLog.d/fix-iar-warnings.txt b/ChangeLog.d/fix-iar-warnings.txt
index 244e8630de27..8a3013232fd5 100644
--- a/ChangeLog.d/fix-iar-warnings.txt
+++ b/ChangeLog.d/fix-iar-warnings.txt
@@ -1,2 +1,2 @@
 Bugfix
-   * Fix IAR compiler warnings. Contributed by Glenn Strauss in #3835.
+   * Fix IAR compiler warnings. Fixes #6924.
diff --git a/library/bignum.c b/library/bignum.c
index 699d2c6de7a0..d915ade639f9 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -2063,6 +2063,7 @@ int mbedtls_mpi_exp_mod(mbedtls_mpi *X, const mbedtls_mpi *A,
     size_t window_bitsize;
     size_t i, j, nblimbs;
     size_t bufsize, nbits;
+    size_t exponent_bits_in_window = 0;
     mbedtls_mpi_uint ei, mm, state;
     mbedtls_mpi RR, T, W[(size_t) 1 << MBEDTLS_MPI_WINDOW_SIZE], WW, Apos;
     int neg;
@@ -2236,7 +2237,6 @@ int mbedtls_mpi_exp_mod(mbedtls_mpi *X, const mbedtls_mpi *A,
     nblimbs = E->n;
     bufsize = 0;
     nbits   = 0;
-    size_t exponent_bits_in_window = 0;
     state   = 0;
 
     while (1) {
diff --git a/library/ecp.c b/library/ecp.c
index a029c22067c2..9051490b129f 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -163,7 +163,8 @@ static int ecp_drbg_seed(ecp_drbg_context *ctx,
     int ret;
     unsigned char secret_bytes[MBEDTLS_ECP_MAX_BYTES];
     /* The list starts with strong hashes */
-    const mbedtls_md_type_t md_type = mbedtls_md_list()[0];
+    const mbedtls_md_type_t md_type =
+        (const mbedtls_md_type_t) (mbedtls_md_list()[0]);
     const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(md_type);
 
     if (secret_len > MBEDTLS_ECP_MAX_BYTES) {
@@ -2062,12 +2063,13 @@ static int ecp_mul_comb_core(const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
     } else
 #endif
     {
+        int have_rng = 1;
+
         /* Start with a non-zero point and randomize its coordinates */
         i = d;
         MBEDTLS_MPI_CHK(ecp_select_comb(grp, R, T, T_size, x[i]));
         MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&R->Z, 1));
 
-        int have_rng = 1;
 #if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
         if (f_rng == NULL) {
             have_rng = 0;
@@ -2172,6 +2174,7 @@ static int ecp_mul_comb_after_precomp(const mbedtls_ecp_group *grp,
     unsigned char parity_trick;
     unsigned char k[COMB_MAX_D + 1];
     mbedtls_ecp_point *RR = R;
+    int have_rng = 1;
 
 #if defined(MBEDTLS_ECP_RESTARTABLE)
     if (rs_ctx != NULL && rs_ctx->rsm != NULL) {
@@ -2208,7 +2211,6 @@ static int ecp_mul_comb_after_precomp(const mbedtls_ecp_group *grp,
      *
      * Avoid the leak by randomizing coordinates before we normalize them.
      */
-    int have_rng = 1;
 #if defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
     if (f_rng == NULL) {
         have_rng = 0;