Allow R and A to point to same mpi in mpi_div_mpi
(cherry picked from commit f02c5642d0f19281e7c30d849bf8cd94703a9bd5 and
from commit 50546921ac8250d1884c41fd9dc7a645007d4103)
diff --git a/ChangeLog b/ChangeLog
index 60e0f77..e562139 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,8 @@
#52)
* Fixed possible segfault in mpi_shift_r() (found by Manuel
Pégourié-Gonnard)
+ * Allow R and A to point to same mpi in mpi_div_mpi (found by Manuel
+ Pégourié-Gonnard)
Security
* Fixed potential memory zeroization on miscrafted RSA key (found by Eloi
diff --git a/library/bignum.c b/library/bignum.c
index acaba6a..079b58e 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1196,9 +1196,9 @@
if( R != NULL )
{
mpi_shift_r( &X, k );
+ X.s = A->s;
mpi_copy( R, &X );
- R->s = A->s;
if( mpi_cmp_int( R, 0 ) == 0 )
R->s = 1;
}
@@ -1400,19 +1400,6 @@
return( POLARSSL_ERR_MPI_BAD_INPUT_DATA );
/*
- * Compensate for negative A (and correct at the end)
- */
- neg = ( A->s == -1 );
-
- mpi_init( &Apos );
- if( neg )
- {
- MPI_CHK( mpi_copy( &Apos, A ) );
- Apos.s = 1;
- A = &Apos;
- }
-
- /*
* Init temps and window size
*/
mpi_montg_init( &mm, N );
@@ -1433,6 +1420,19 @@
MPI_CHK( mpi_grow( &T, j * 2 ) );
/*
+ * Compensate for negative A (and correct at the end)
+ */
+ neg = ( A->s == -1 );
+
+ mpi_init( &Apos );
+ if( neg )
+ {
+ MPI_CHK( mpi_copy( &Apos, A ) );
+ Apos.s = 1;
+ A = &Apos;
+ }
+
+ /*
* If 1st call, pre-compute R^2 mod N
*/
if( _RR == NULL || _RR->p == NULL )
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index 596b7df..70d9b4f 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -514,21 +514,21 @@
BEGIN_CASE
mpi_mod_mpi:radix_X:input_X:radix_Y:input_Y:radix_A:input_A:div_result
{
- mpi X, Y, Z, A;
+ mpi X, Y, A;
int res;
- mpi_init( &X ); mpi_init( &Y ); mpi_init( &Z ); mpi_init( &A );
+ mpi_init( &X ); mpi_init( &Y ); mpi_init( &A );
TEST_ASSERT( mpi_read_string( &X, {radix_X}, {input_X} ) == 0 );
TEST_ASSERT( mpi_read_string( &Y, {radix_Y}, {input_Y} ) == 0 );
TEST_ASSERT( mpi_read_string( &A, {radix_A}, {input_A} ) == 0 );
- res = mpi_mod_mpi( &Z, &X, &Y );
+ res = mpi_mod_mpi( &X, &X, &Y );
TEST_ASSERT( res == {div_result} );
if( res == 0 )
{
- TEST_ASSERT( mpi_cmp_mpi( &Z, &A ) == 0 );
+ TEST_ASSERT( mpi_cmp_mpi( &X, &A ) == 0 );
}
- mpi_free( &X ); mpi_free( &Y ); mpi_free( &Z ); mpi_free( &A );
+ mpi_free( &X ); mpi_free( &Y ); mpi_free( &A );
}
END_CASE