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mbedtls_mpi_mod_read/write: restrict pre-conditions

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Require equality for the number of limbs in the modulus and the residue.
This makes these functions consistent with residue_setup().

Signed-off-by: Janos Follath <janos.follath@arm.com>
This commit is contained in:
Janos Follath 2022-11-26 14:59:27 +00:00
parent 75b9f0fd2e
commit d7bb35257b
2 changed files with 17 additions and 5 deletions
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4
library/bignum_mod.c
View file

@ -207,7 +207,7 @@ int mbedtls_mpi_mod_read( mbedtls_mpi_mod_residue *r,
/* Do our best to check if r and m have been set up */
if ( r->limbs == 0 || m->limbs == 0 )
goto cleanup;
if ( r->limbs > m->limbs )
if ( r->limbs != m->limbs )
goto cleanup;
ret = mbedtls_mpi_mod_raw_read( r->p, m, buf, buflen, ext_rep );
@ -235,7 +235,7 @@ int mbedtls_mpi_mod_write( const mbedtls_mpi_mod_residue *r,
/* Do our best to check if r and m have been set up */
if ( r->limbs == 0 || m->limbs == 0 )
goto cleanup;
if ( r->limbs > m->limbs )
if ( r->limbs != m->limbs )
goto cleanup;
if ( m->int_rep == MBEDTLS_MPI_MOD_REP_MONTGOMERY)

18
tests/suites/test_suite_bignum_mod.function
View file

@ -148,13 +148,23 @@ void mpi_mod_io_neg( char * input_N, data_t * buf, int ret )
TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
mbedtls_mpi_mod_write( &rn, &m, buf->x, buf->len, endian ) );
/* Fail for r_limbs > m->limbs */
r.limbs = m.limbs + 1;
/* Fail for r_limbs < m->limbs */
r.limbs--;
TEST_ASSERT( r.limbs < m.limbs );
TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
mbedtls_mpi_mod_read( &r, &m, buf->x, buf->len, endian ) );
TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
mbedtls_mpi_mod_write( &r, &m, buf->x, buf->len, endian ) );
r.limbs = r_limbs;
r.limbs++;
/* Fail for r_limbs > m->limbs */
m.limbs--;
TEST_ASSERT( r.limbs > m.limbs );
TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
mbedtls_mpi_mod_read( &r, &m, buf->x, buf->len, endian ) );
TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
mbedtls_mpi_mod_write( &r, &m, buf->x, buf->len, endian ) );
m.limbs++;
/* Test the read */
TEST_EQUAL( ret, mbedtls_mpi_mod_read( &r, &m, buf->x, buf->len, endian ) );
@ -163,7 +173,9 @@ void mpi_mod_io_neg( char * input_N, data_t * buf, int ret )
if ( r.limbs > 1 && ret == 0 )
TEST_EQUAL( MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL,
mbedtls_mpi_mod_write( &r, &m, buf->x, 1, endian ) );
exit:
mbedtls_mpi_mod_residue_release( &r );
mbedtls_mpi_mod_modulus_free( &m );
mbedtls_free( N );
mbedtls_free( R );