Do not produce a corrupt BIGNUM when adding 0 to 0 using BN_add_word().

ok markus@

2 files changed, 6 insertions, 0 deletions

diff --git a/src/lib/libcrypto/bn/bn_word.c b/src/lib/libcrypto/bn/bn_word.c
index 988e0ca7b3..ab858d70ff 100644
--- a/src/lib/libcrypto/bn/bn_word.c
+++ b/src/lib/libcrypto/bn/bn_word.c
@@ -110,6 +110,9 @@ int BN_add_word(BIGNUM *a, BN_ULONG w)
         BN_ULONG l;
         int i;
 
+        if ((w & BN_MASK2) == 0)
+                return(1);
+
         if (a->neg)
                 {
                 a->neg=0;
diff --git a/src/lib/libssl/src/crypto/bn/bn_word.c b/src/lib/libssl/src/crypto/bn/bn_word.c
index 988e0ca7b3..ab858d70ff 100644
--- a/src/lib/libssl/src/crypto/bn/bn_word.c
+++ b/src/lib/libssl/src/crypto/bn/bn_word.c
@@ -110,6 +110,9 @@ int BN_add_word(BIGNUM *a, BN_ULONG w)
         BN_ULONG l;
         int i;
 
+        if ((w & BN_MASK2) == 0)
+                return(1);
+
         if (a->neg)
                 {
                 a->neg=0;