From e6bcad3f797515bc9961593ca4100ce955ea693b Mon Sep 17 00:00:00 2001
From: Peter Kolbus <peter.kolbus@garmin.com>
Date: Tue, 11 Dec 2018 14:01:44 -0600
Subject: [PATCH] Fix DEADCODE in mbedtls_mpi_exp_mod()

In mbedtls_mpi_exp_mod(), the limit check on wsize is never true when
MBEDTLS_MPI_WINDOW_SIZE is at least 6. Wrap in a preprocessor guard
to remove the dead code and resolve a Coverity finding from the
DEADCODE checker.

Change-Id: Ice7739031a9e8249283a04de11150565b613ae89
---
 library/bignum.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/library/bignum.c b/library/bignum.c
index 87015af0c..47e4529be 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1869,8 +1869,10 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
     wsize = ( i > 671 ) ? 6 : ( i > 239 ) ? 5 :
             ( i >  79 ) ? 4 : ( i >  23 ) ? 3 : 1;
 
+#if( MBEDTLS_MPI_WINDOW_SIZE < 6 )
     if( wsize > MBEDTLS_MPI_WINDOW_SIZE )
         wsize = MBEDTLS_MPI_WINDOW_SIZE;
+#endif
 
     j = N->n + 1;
     MBEDTLS_MPI_CHK( mbedtls_mpi_grow( X, j ) );