1 files changed, 11 insertions, 6 deletions

diff --git a/src/lib/libcrypto/bn/bn_word.c b/src/lib/libcrypto/bn/bn_word.c
index 73157a7d43..cd59baa2c4 100644
--- a/src/lib/libcrypto/bn/bn_word.c
+++ b/src/lib/libcrypto/bn/bn_word.c
@@ -115,7 +115,7 @@ int BN_add_word(BIGNUM *a, BN_ULONG w)
                 a->neg=0;
                 i=BN_sub_word(a,w);
                 if (!BN_is_zero(a))
-                        a->neg=1;
+                        a->neg=!(a->neg);
                 return(i);
                 }
         w&=BN_MASK2;
@@ -140,7 +140,7 @@ int BN_sub_word(BIGNUM *a, BN_ULONG w)
         {
         int i;
 
-        if (a->neg)
+        if (BN_is_zero(a) || a->neg)
                 {
                 a->neg=0;
                 i=BN_add_word(a,w);
@@ -182,11 +182,16 @@ int BN_mul_word(BIGNUM *a, BN_ULONG w)
         w&=BN_MASK2;
         if (a->top)
                 {
-                ll=bn_mul_words(a->d,a->d,a->top,w);
-                if (ll)
+                if (w == 0)
+                        BN_zero(a);
+                else
                         {
-                        if (bn_wexpand(a,a->top+1) == NULL) return(0);
-                        a->d[a->top++]=ll;
+                        ll=bn_mul_words(a->d,a->d,a->top,w);
+                        if (ll)
+                                {
+                                if (bn_wexpand(a,a->top+1) == NULL) return(0);
+                                a->d[a->top++]=ll;
+                                }
                         }
                 }
         return(1);