fix one possible NULL bug in d0_bignum-gmp

diff --git a/d0_bignum-gmp.c b/d0_bignum-gmp.c
index 95b95e25aaf4c08164ef15f33cbacc576fc4b92e..d5da8b5889d64ee68e36febcc368d99487221952 100644 (file)
--- a/d0_bignum-gmp.c
+++ b/d0_bignum-gmp.c
@@ -74,7 +74,8 @@ static void *reallocate_function (void *ptr, size_t old_size, size_t new_size)
        if(old_size == new_size)
                return ptr;
        data = d0_malloc(new_size);
-       memcpy(data, ptr, (old_size < new_size) ? old_size : new_size);
+       if(ptr && data)
+               memcpy(data, ptr, (old_size < new_size) ? old_size : new_size);
        d0_free(ptr);
        return data;
 }