Re: master 583995c: GnuTLS HMAC and symmetric cipher support

[Paul Eggert <eggert@cs.ucla.edu>]

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Glenn Morris wrote:
> Since 583995c, make check on hydra crashes when loading the gnutls tests.
> It uses gnutls 3.2.21. I installed that on my rhel7 system (with
> --disable-non-suiteb-curves) and reproduced the crash. The

I don't see how the crash can occur with vanilla GnuTLS 3.2.21, as its 
gnutls_cipher_list returns a list of IDs that does not contain 
GNUTLS_CIPHER_UNKNOWN. Perhaps you were using a modified GnuTLS 3.2.21. Or 
possibly I'm misreading the GnuTLS source code, though I don't see how.

As you're observing the problem I installed the attached, which is similar to 
the patch that worked for you.

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From 376151481b2172dbb08d25bb5946f0f627f7453d Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 18 Jul 2017 00:37:03 -0700
Subject: [PATCH] Port gnutls.c to older (buggier?) GnuTLS

Problem reported for GnuTLS 3.2.1 by Glenn Morris in:
http://lists.gnu.org/archive/html/emacs-devel/2017-07/msg00716.html
http://lists.gnu.org/archive/html/emacs-devel/2017-07/msg00742.html
Although I don't see how this bug can occur with vanilla GnuTLS 3.2.1,
perhaps hydra was using a modified GnuTLS.
* src/gnutls.c (Fgnutls_ciphers): Don't assume GNUTLS_CIPHER_NULL
is at the end of the list returned by gnutls_cipher_list,
or that the earlier ciphers all have non-null names.
---
 src/gnutls.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/gnutls.c b/src/gnutls.c
index 9fbaea2..e406d66 100644
--- a/src/gnutls.c
+++ b/src/gnutls.c
@@ -1854,12 +1854,17 @@ The alist key is the cipher name. */)
 
 #ifdef HAVE_GNUTLS3_CIPHER
   const gnutls_cipher_algorithm_t *gciphers = gnutls_cipher_list ();
-  for (ptrdiff_t pos = 0; gciphers[pos] != GNUTLS_CIPHER_NULL; pos++)
+  for (ptrdiff_t pos = 0; gciphers[pos] != 0; pos++)
     {
       gnutls_cipher_algorithm_t gca = gciphers[pos];
+      if (gca == GNUTLS_CIPHER_NULL)
+	continue;
+      char const *cipher_name = gnutls_cipher_get_name (gca);
+      if (!cipher_name)
+	continue;
 
       /* A symbol representing the GnuTLS cipher.  */
-      Lisp_Object cipher_symbol = intern (gnutls_cipher_get_name (gca));
+      Lisp_Object cipher_symbol = intern (cipher_name);
 
       ptrdiff_t cipher_tag_size = gnutls_cipher_get_tag_size (gca);
 
-- 
2.7.4