1 files changed, 6 insertions, 0 deletions

diff --git a/src/lib/libcrypto/bn/bn_lib.c b/src/lib/libcrypto/bn/bn_lib.c
index a016cb7f53..8abe095af2 100644
--- a/src/lib/libcrypto/bn/bn_lib.c
+++ b/src/lib/libcrypto/bn/bn_lib.c
@@ -397,6 +397,12 @@ BIGNUM *bn_dup_expand(const BIGNUM *b, int words)
         {
         BIGNUM *r = NULL;
 
+        /* This function does not work if
+         *      words <= b->dmax && top < words
+         * because BN_dup() does not preserve 'dmax'!
+         * (But bn_dup_expand() is not used anywhere yet.)
+         */
+        
         if (words > b->dmax)
                 {
                 BN_ULONG *a = bn_expand_internal(b, words);