Return the signature length after successful signing operation

This is required behavior of the EVP_DigestSign() API, but seemingly
almost nothing uses this. Well, turns out ldns does.

Reported by Stephane. Helpful comments by sthen.

ok jsing

1 files changed, 3 insertions, 1 deletions

diff --git a/src/lib/libcrypto/ec/ecx_methods.c b/src/lib/libcrypto/ec/ecx_methods.c
index 26fef18381..8510d1a471 100644
--- a/src/lib/libcrypto/ec/ecx_methods.c
+++ b/src/lib/libcrypto/ec/ecx_methods.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: ecx_methods.c,v 1.4 2022/11/26 16:08:52 tb Exp $ */
+/*      $OpenBSD: ecx_methods.c,v 1.5 2023/03/15 06:34:07 tb Exp $ */
 /*
  * Copyright (c) 2022 Joel Sing <jsing@openbsd.org>
  *
@@ -741,6 +741,8 @@ pkey_ecx_digestsign(EVP_MD_CTX *md_ctx, unsigned char *out_sig,
             ecx_key->priv_key))
                 return 0;
 
+        *out_sig_len = ecx_sig_size(pkey_ctx->pkey);
+
         return 1;
 }