AuroraMiddleware/mbedtls
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Fix potential DoS by limiting number sizes in exponentiation

Browse Source 
Check that the exponent and modulus is below `MBEDTLS_MPI_MAX_BITS` before
performing a time expensive operation (modular exponentiation). This prevents
a potential DoS from Diffie-Hellman computations with extremely
large key sizes.

Signed-off-by: Chris Jones <christopher.jones@arm.com>
This commit is contained in:
Chris Jones 2020-11-25 15:12:39 +00:00
parent bbc6032444
commit 9246d04150
1 changed files with 4 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
library/bignum.c
View File

@ -2115,6 +2115,10 @@ 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 );
if( mbedtls_mpi_bitlen( E ) > MBEDTLS_MPI_MAX_BITS ||
mbedtls_mpi_bitlen( N ) > MBEDTLS_MPI_MAX_BITS )
return ( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
/*
* Init temps and window size
*/