From 55e13d40b3fb1754d98b1aefa94e65f981a1174f Mon Sep 17 00:00:00 2001
From: Sean Parkinson <sean@wolfssl.com>
Date: Tue, 12 Apr 2022 08:53:16 +1000
Subject: [PATCH] SP Math

sp_read_radix_10: check _sp_add_d doesn't error due to overflow
_sp_add_d: Don't change value of used for result until it is known to be
valid.
---
 wolfcrypt/src/sp_int.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/wolfcrypt/src/sp_int.c b/wolfcrypt/src/sp_int.c
index 284b6bc6a..43a85a48f 100644
--- a/wolfcrypt/src/sp_int.c
+++ b/wolfcrypt/src/sp_int.c
@@ -5219,11 +5219,13 @@ static int _sp_add_d(sp_int* a, sp_int_digit d, sp_int* r)
             }
         }
         if (i == a->used) {
-            r->used++;
-            if (i < r->size)
+            if (i < r->size) {
+                r->used++;
                 r->dp[i] = 1;
-            else
+            }
+            else {
                 err = MP_VAL;
+            }
         }
     }
     if (err == MP_OKAY) {
@@ -14889,7 +14891,10 @@ static int _sp_read_radix_10(sp_int* a, const char* in)
         if (err != MP_OKAY) {
             break;
         }
-        (void)_sp_add_d(a, ch, a);
+        err = _sp_add_d(a, ch, a);
+        if (err != MP_OKAY) {
+            break;
+        }
     }
 #ifdef WOLFSSL_SP_INT_NEGATIVE
     if ((err == MP_OKAY) && sp_iszero(a)) {