diff options
| author | Jens Wiklander <jens.wiklander@linaro.org> | 2019-05-21 22:52:10 +0200 |
|---|---|---|
| committer | Jérôme Forissier <jerome@forissier.org> | 2019-05-22 12:59:03 +0200 |
| commit | 41e5aa8f18c4d48083341ff3df9e75f0c77cf703 (patch) | |
| tree | bbcafebe3b3775d63ea298b08bdc080f24c244a0 | |
| parent | 628e1eb09852e7b260077db810dcc09045481916 (diff) | |
libmbedtls: mbedtls_mpi_exp_mod(): reduce stack usage
68df6eb0f256 ("libmbedtls: mbedtls_mpi_exp_mod(): reduce stack usage")
from branch import/mbedtls-2.16.0
The W variable is 3072 bytes on AArch64 with MBEDTLS_MPI_WINDOW_SIZE set
to 6 for maximum performance. Instead of allocating such a large
variable on the stack use mempool_alloc().
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
| -rw-r--r-- | lib/libmbedtls/mbedtls/library/bignum.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/lib/libmbedtls/mbedtls/library/bignum.c b/lib/libmbedtls/mbedtls/library/bignum.c index 8279d7d6..4c1840a0 100644 --- a/lib/libmbedtls/mbedtls/library/bignum.c +++ b/lib/libmbedtls/mbedtls/library/bignum.c @@ -1788,7 +1788,9 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, size_t i, j, nblimbs; size_t bufsize, nbits; mbedtls_mpi_uint ei, mm, state; - mbedtls_mpi RR, T, W[ 2 << MBEDTLS_MPI_WINDOW_SIZE ], Apos; + mbedtls_mpi RR, T, Apos; + mbedtls_mpi *W; + const size_t array_size_W = 2 << MBEDTLS_MPI_WINDOW_SIZE; int neg; MPI_VALIDATE_RET( X != NULL ); @@ -1802,13 +1804,18 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, if( mbedtls_mpi_cmp_int( E, 0 ) < 0 ) return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA ); + W = mempool_alloc( mbedtls_mpi_mempool, + sizeof( mbedtls_mpi ) * array_size_W ); + if( W == NULL ) + return( MBEDTLS_ERR_MPI_ALLOC_FAILED ); + /* * Init temps and window size */ mbedtls_mpi_montg_init( &mm, N ); mbedtls_mpi_init_mempool( &RR ); mbedtls_mpi_init_mempool( &T ); mbedtls_mpi_init_mempool( &Apos ); - for( i = 0; i < ARRAY_SIZE(W); i++ ) + for( i = 0; i < array_size_W; i++ ) mbedtls_mpi_init_mempool( W + i ); i = mbedtls_mpi_bitlen( E ); @@ -1981,8 +1988,9 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, cleanup: - for( i = 0; i < ARRAY_SIZE(W); i++ ) + for( i = 0; i < array_size_W; i++ ) mbedtls_mpi_free( W + i ); + mempool_free( mbedtls_mpi_mempool , W ); mbedtls_mpi_free( &T ); mbedtls_mpi_free( &Apos ); |