Move wNAF[], wNAF_len[], wsize[] to the stack

Again, we know their sizes (always 2), so we can avoid allocating and
freeing them. Also remove the extra "pivot" element. It's not needed.

ok djm

1 files changed, 6 insertions, 32 deletions

diff --git a/src/lib/libcrypto/ec/ec_mult.c b/src/lib/libcrypto/ec/ec_mult.c
index 598694d80a..756abf1a3d 100644
--- a/src/lib/libcrypto/ec/ec_mult.c
+++ b/src/lib/libcrypto/ec/ec_mult.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_mult.c,v 1.39 2024/11/22 00:15:38 tb Exp $ */
+/* $OpenBSD: ec_mult.c,v 1.40 2024/11/22 00:52:39 tb Exp $ */
 /*
  * Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project.
  */
@@ -227,6 +227,9 @@ int
 ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *m,
     const EC_POINT *point, const BIGNUM *n, BN_CTX *ctx)
 {
+        signed char *wNAF[2] = { 0 };
+        size_t wNAF_len[2] = { 0 };
+        size_t wsize[2] = { 0 };
         const EC_POINT *generator = NULL;
         EC_POINT *tmp = NULL;
         EC_POINT **row[2] = { 0 };
@@ -234,9 +237,6 @@ ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *m,
         size_t i, j;
         int k;
         int r_is_inverted = 0;
-        size_t *wsize = NULL;   /* individual window sizes */
-        signed char **wNAF = NULL;      /* individual wNAFs */
-        size_t *wNAF_len = NULL;
         size_t max_len = 0;
         size_t num_val;
         EC_POINT **val = NULL;  /* precomputation */
@@ -259,23 +259,6 @@ ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *m,
 
         totalnum = 2;
 
-        /* includes space for pivot */
-        wNAF = reallocarray(NULL, (totalnum + 1), sizeof wNAF[0]);
-        if (wNAF == NULL) {
-                ECerror(ERR_R_MALLOC_FAILURE);
-                goto err;
-        }
-
-        wNAF[0] = NULL;         /* preliminary pivot */
-
-        wsize = reallocarray(NULL, totalnum, sizeof wsize[0]);
-        wNAF_len = reallocarray(NULL, totalnum, sizeof wNAF_len[0]);
-
-        if (wsize == NULL || wNAF_len == NULL) {
-                ECerror(ERR_R_MALLOC_FAILURE);
-                goto err;
-        }
-
         /* num_val will be the total number of temporarily precomputed points */
         num_val = 0;
 
@@ -285,7 +268,6 @@ ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *m,
                 bits = i < 1 ? BN_num_bits(n) : BN_num_bits(m);
                 wsize[i] = EC_window_bits_for_scalar_size(bits);
                 num_val += (size_t) 1 << (wsize[i] - 1);
-                wNAF[i + 1] = NULL;     /* make sure we always have a pivot */
                 wNAF[i] = compute_wNAF(i < 1 ? n : m, wsize[i], &wNAF_len[i]);
                 if (wNAF[i] == NULL)
                         goto err;
@@ -403,16 +385,8 @@ ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *m,
 
  err:
         EC_POINT_free(tmp);
-        free(wsize);
-        free(wNAF_len);
-        if (wNAF != NULL) {
-                signed char **w;
-
-                for (w = wNAF; *w != NULL; w++)
-                        free(*w);
-
-                free(wNAF);
-        }
+        free(wNAF[0]);
+        free(wNAF[1]);
         if (val != NULL) {
                 for (v = val; *v != NULL; v++)
                         EC_POINT_free(*v);