commit a17ad48e2d139d171dfe3bb59703b41eb869b18b
author Minos Galanakis <minos.galanakis@arm.com> Wed Nov 16 16:29:15 2022 +0000
committer Janos Follath <janos.follath@arm.com> Fri Nov 25 17:55:00 2022 +0000
tree 97a39505a6eaba8cb45f9558b808796425a2e096
parent 8f242706303b4b681fbe4e350ece31928b151098

bignum_mod: Fixed an issue with input checking in `mpi_mod_residue_setup`

This patch is inverting the input type checking logic in the method,
in order to ensure that residue < modulus.

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>

library/bignum_mod.c

diff --git a/library/bignum_mod.c b/library/bignum_mod.c
index a4ed32b..6c13b4b 100644
--- a/library/bignum_mod.c
+++ b/library/bignum_mod.c
@@ -39,7 +39,7 @@
                                    mbedtls_mpi_uint *p,
                                    size_t p_limbs )
 {
-    if( p_limbs < m->limbs || !mbedtls_mpi_core_lt_ct( m->p, p, p_limbs ) )
+    if( p_limbs > m->limbs || !mbedtls_mpi_core_lt_ct( p, m->p, m->limbs ) )
         return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
 
     r->limbs = m->limbs;