Improved on the previous fix and added a test case to cover both types
of carries.
diff --git a/library/bignum.c b/library/bignum.c
index e46ce0b..975b6f8 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -889,22 +889,11 @@
{
int ret;
size_t i, j;
- mpi_uint *o, *p, c;
- mpi TB;
+ mpi_uint *o, *p, c, tmp;
if( X == B )
{
- B = A; A = X;
-
- if( B == A )
- {
- // Making a temporary copy instead of shifting by one to deny
- // the possibility of corresponding side-channel attacks.
- mpi_init( &TB );
- MPI_CHK( mpi_copy( &TB, B ) );
-
- B = &TB;
- }
+ const mpi *T = A; A = X; B = T;
}
if( X != A )
@@ -923,10 +912,14 @@
o = B->p; p = X->p; c = 0;
+ /*
+ * tmp is used because it might happen that p == o
+ */
for( i = 0; i < j; i++, o++, p++ )
{
+ tmp= *o;
*p += c; c = ( *p < c );
- *p += *o; c += ( *p < *o );
+ *p += tmp; c += ( *p < tmp );
}
while( c != 0 )
@@ -941,10 +934,13 @@
}
cleanup:
+<<<<<<< HEAD
if( &TB == B )
{
mpi_free( &TB );
}
+=======
+>>>>>>> 6c9226809370... Improved on the previous fix and added a test case to cover both types
return( ret );
}
diff --git a/tests/suites/test_suite_mpi.data b/tests/suites/test_suite_mpi.data
index 76c9e3e..a8da378 100644
--- a/tests/suites/test_suite_mpi.data
+++ b/tests/suites/test_suite_mpi.data
@@ -301,6 +301,9 @@
Test mpi_add_mpi inplace #2
mpi_add_mpi_inplace:10:"643808006803554439230129854961492699151386107534013432918073439524138264842370630061369715394739134090922937332590384720397133335969549256322620979036686633213903952966175107096769180017646161851573147596390153":10:"1287616013607108878460259709922985398302772215068026865836146879048276529684741260122739430789478268181845874665180769440794266671939098512645241958073373266427807905932350214193538360035292323703146295192780306"
+Test mpi_add_mpi inplace #3
+mpi_add_mpi_inplace:16:"ffffffffffffffffffffffffffffffff":16:"01fffffffffffffffffffffffffffffffe"
+
Test mpi_add_int #1
mpi_add_int:10:"2039568783564019774057658669290345772801939933143482630947726464532830627227012776329":9871232:10:"2039568783564019774057658669290345772801939933143482630947726464532830627227022647561"