From ce0136e9682b81582f412647faa13ba00ad5bcf6 Mon Sep 17 00:00:00 2001
From: John Safranek <john@wolfssl.com>
Date: Wed, 20 Nov 2019 13:55:57 -0800
Subject: [PATCH] Maintenance: Integers In TFM and Integer, rshb() shouldn't
 try to shift a value that is 0. This leads to using a negative offset to a
 pointer, but isn't used.

---
 wolfcrypt/src/integer.c | 2 ++
 wolfcrypt/src/tfm.c     | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/wolfcrypt/src/integer.c b/wolfcrypt/src/integer.c
index e94c36e11..7c1536eda 100644
--- a/wolfcrypt/src/integer.c
+++ b/wolfcrypt/src/integer.c
@@ -572,6 +572,8 @@ void mp_rshb (mp_int *c, int x)
     mp_digit r, rr;
     mp_digit D = x;
 
+    if (mp_iszero(c)) return;
+
     /* mask */
     mask = (((mp_digit)1) << D) - 1;
 
diff --git a/wolfcrypt/src/tfm.c b/wolfcrypt/src/tfm.c
index f0fb014ac..e6713f9ca 100644
--- a/wolfcrypt/src/tfm.c
+++ b/wolfcrypt/src/tfm.c
@@ -3174,6 +3174,8 @@ void fp_rshb(fp_int *c, int x)
     fp_digit r, rr;
     fp_digit D = x;
 
+    if (fp_iszero(c)) return;
+
     /* mask */
     mask = (((fp_digit)1) << D) - 1;