yuzu-emu/mbedtls
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

mpi_exp_mod: fix out of bounds access

Browse source 
The table size was set before the configured window size bound was
applied which lead to out of bounds access when the configured window
size bound is less.

Signed-off-by: Janos Follath <janos.follath@arm.com>
This commit is contained in:
Janos Follath 2022-11-22 10:18:06 +00:00
parent 9c09326572
commit 060009518b
1 changed files with 2 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
library/bignum.c
View file

@ -2005,13 +2005,14 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
window_bitsize = ( i > 671 ) ? 6 : ( i > 239 ) ? 5 :
( i > 79 ) ? 4 : ( i > 23 ) ? 3 : 1;
const size_t w_table_used_size = ( (size_t)1 << window_bitsize ) + 1;
#if( MBEDTLS_MPI_WINDOW_SIZE < 6 )
if( window_bitsize > MBEDTLS_MPI_WINDOW_SIZE )
window_bitsize = MBEDTLS_MPI_WINDOW_SIZE;
#endif
const size_t w_table_used_size = ( (size_t) 1 << window_bitsize ) + 1;
/*
* This function is not constant-trace: its memory accesses depend on the
* exponent value. To defend against timing attacks, callers (such as RSA