Avoid potential overflow to the sign bit when shifting left 24 places

[openssl.git] / crypto / bn / bn_mpi.c

diff --git a/crypto/bn/bn_mpi.c b/crypto/bn/bn_mpi.c
index ff7eabf80af9a8716d35490235e302283af86fee..d2be44e2bdbe4e6a5848785d6843d1f4bbd0a802 100644 (file)
--- a/crypto/bn/bn_mpi.c
+++ b/crypto/bn/bn_mpi.c
@@ -9,7 +9,7 @@
 
 #include <stdio.h>
 #include "internal/cryptlib.h"
-#include "bn_lcl.h"
+#include "bn_local.h"
 
 int BN_bn2mpi(const BIGNUM *a, unsigned char *d)
 {
@@ -45,7 +45,7 @@ BIGNUM *BN_mpi2bn(const unsigned char *d, int n, BIGNUM *ain)
     int neg = 0;
     BIGNUM *a = NULL;
 
-    if (n < 4) {
+    if (n < 4 || (d[0] & 0x80) != 0) {
         BNerr(BN_F_BN_MPI2BN, BN_R_INVALID_LENGTH);
         return NULL;
     }