Merge remote-tracking branch 'origin/pr/2317' into development

* origin/pr/2317:
  Update ChangeLog
  all.sh: Test MBEDTLS_MPI_WINDOW_SIZE=1
  Fix DEADCODE in mbedtls_mpi_exp_mod()

ChangeLog

@@ -84,6 +84,10 @@ Changes
      Illya Gerasymchuk.
    * Return from various debugging routines immediately if the
      provided SSL context is unset.
+   * Remove dead code from bignum.c in the default configuration.
+     Found by Coverity, reported and fixed by Peter Kolbus (Garmin). Fixes #2309.
+   * Add test for minimal value of MBEDTLS_MPI_WINDOW_SIZE to all.sh.
+     Contributed by Peter Kolbus (Garmin).
 
 = mbed TLS 2.16.0 branch released 2018-12-21
 

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 ) );

tests/scripts/all.sh

@@ -1100,6 +1100,16 @@ support_test_mx32 () {
     esac
 }
 
+component_test_min_mpi_window_size () {
+    msg "build: Default + MBEDTLS_MPI_WINDOW_SIZE=1 (ASan build)" # ~ 10s
+    scripts/config.pl set MBEDTLS_MPI_WINDOW_SIZE 1
+    CC=gcc cmake -D CMAKE_BUILD_TYPE:String=Asan .
+    make
+
+    msg "test: MBEDTLS_MPI_WINDOW_SIZE=1 - main suites (inc. selftests) (ASan build)" # ~ 10s
+    make test
+}
+
 component_test_have_int32 () {
     msg "build: gcc, force 32-bit bignum limbs"
     scripts/config.pl unset MBEDTLS_HAVE_ASM