There's a slight possibility that a is 0 in BN_sub_word(), and might

therefore have unallocated parts.  Therefore, a check for the 0 case
is needed, resulting with the same thing as when a is negative.

diff --git a/crypto/bn/bn_word.c b/crypto/bn/bn_word.c
index 7e7ca58842bb92dbd732924a05d247d7aa8f6682..f3bdde969cc376a9344b9d58c6d8c6a97766bcd6 100644 (file)
--- a/crypto/bn/bn_word.c
+++ b/crypto/bn/bn_word.c
@@ -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);