From e17f86d1454e200a7242282eba4cf25131d00184 Mon Sep 17 00:00:00 2001
From: Sean Parkinson <sean@wolfssl.com>
Date: Wed, 14 Jun 2023 08:05:57 +1000
Subject: [PATCH] TFM: fix big endian reading a zero length buffer

Bail early as big endian implementation doesn't handle it.
---
 wolfcrypt/src/tfm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/wolfcrypt/src/tfm.c b/wolfcrypt/src/tfm.c
index 1ab156a24..99be4217e 100644
--- a/wolfcrypt/src/tfm.c
+++ b/wolfcrypt/src/tfm.c
@@ -3697,6 +3697,10 @@ int fp_read_unsigned_bin(fp_int *a, const unsigned char *b, int c)
   /* zero the int */
   fp_zero (a);
 
+  if (c == 0) {
+      return FP_OKAY;
+  }
+
   /* if input b excess max, then truncate */
   if (c > 0 && (word32)c > maxC) {
      int excess = (c - maxC);