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mbedtls_mpi_mod_write: prevent data corruption

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The function wasn't converting back data to internal representation when
writing it out.

Signed-off-by: Janos Follath <janos.follath@arm.com>
This commit is contained in:
Janos Follath 2022-11-26 15:39:02 +00:00
parent d7bb35257b
commit 8dfc8c41b7
2 changed files with 24 additions and 2 deletions
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16
library/bignum_mod.c
View file

@ -231,6 +231,7 @@ int mbedtls_mpi_mod_write( const mbedtls_mpi_mod_residue *r,
mbedtls_mpi_mod_ext_rep ext_rep )
{
int ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
int conv_ret = 0;
/* Do our best to check if r and m have been set up */
if ( r->limbs == 0 || m->limbs == 0 )
@ -238,12 +239,23 @@ int mbedtls_mpi_mod_write( const mbedtls_mpi_mod_residue *r,
if ( r->limbs != m->limbs )
goto cleanup;
if ( m->int_rep == MBEDTLS_MPI_MOD_REP_MONTGOMERY)
ret = mbedtls_mpi_mod_raw_from_mont_rep( r->p, m );
if ( m->int_rep == MBEDTLS_MPI_MOD_REP_MONTGOMERY )
{
conv_ret = mbedtls_mpi_mod_raw_from_mont_rep( r->p, m );
if( conv_ret != 0 )
goto cleanup;
}
ret = mbedtls_mpi_mod_raw_write( r->p, m, buf, buflen, ext_rep );
if ( m->int_rep == MBEDTLS_MPI_MOD_REP_MONTGOMERY )
conv_ret = mbedtls_mpi_mod_raw_to_mont_rep( r->p, m );
cleanup:
if ( ret == 0 )
ret = conv_ret;
return ( ret );
}
/* END MERGE SLOT 7 */

10
tests/suites/test_suite_bignum_mod.function
View file

@ -187,9 +187,11 @@ void mpi_mod_io( char * input_N, data_t * input_A, int endian )
{
mbedtls_mpi_uint *N = NULL;
mbedtls_mpi_uint *R = NULL;
mbedtls_mpi_uint *R_COPY = NULL;
unsigned char *r_buff = NULL;
mbedtls_mpi_mod_modulus m;
mbedtls_mpi_mod_residue r;
mbedtls_mpi_mod_residue r_copy;
size_t n_limbs, n_bytes, a_bytes;
mbedtls_mpi_mod_modulus_init( &m );
@ -201,6 +203,7 @@ void mpi_mod_io( char * input_N, data_t * input_A, int endian )
/* Allocate the memory for intermediate data structures */
ASSERT_ALLOC( R, n_bytes );
ASSERT_ALLOC( R_COPY, n_bytes );
ASSERT_ALLOC( r_buff, a_bytes );
/* Test that input's size is not greater to modulo's */
@ -219,11 +222,18 @@ void mpi_mod_io( char * input_N, data_t * input_A, int endian )
TEST_EQUAL( 0, mbedtls_mpi_mod_write( &r, &m, r_buff, a_bytes,
endian ) );
/* Make sure that writing didn't change the value of r */
TEST_EQUAL( 0, mbedtls_mpi_mod_residue_setup( &r_copy, &m, R_COPY, n_limbs ) );
TEST_EQUAL( 0, mbedtls_mpi_mod_read( &r_copy, &m, input_A->x, input_A->len,
endian ) );
ASSERT_COMPARE( r.p, r.limbs, r_copy.p, r_copy.limbs );
ASSERT_COMPARE( r_buff, a_bytes, input_A->x, a_bytes );
exit:
mbedtls_mpi_mod_modulus_free( &m );
mbedtls_free( N );
mbedtls_free( R );
mbedtls_free( R_COPY );
mbedtls_free( r_buff );
}
/* END_CASE */