upstream: When choosing a prime from the moduli file, avoid

re-using the linenum variable for something that is not a line number to
avoid the confusion that resulted in the bug in rev. 1.64.  This also lets us
pass the actual linenum to parse_prime() so the error messages include the
correct line number.  OK markus@ some time ago.

OpenBSD-Commit-ID: 4d8e5d3e924d6e8eb70053e3defa23c151a00084

1 files changed, 8 insertions, 6 deletions

diff --git a/dh.c b/dh.c
index f3ed38829..657b32da3 100644
--- a/dh.c
+++ b/dh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dh.c,v 1.66 2018/08/04 00:55:06 djm Exp $ */
+/* $OpenBSD: dh.c,v 1.68 2018/09/17 15:40:14 millert Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  *
@@ -188,15 +188,17 @@ choose_dh(int min, int wantbits, int max)
                 logit("WARNING: no suitable primes in %s", _PATH_DH_MODULI);
                 return (dh_new_group_fallback(max));
         }
+        which = arc4random_uniform(bestcount);
 
         linenum = 0;
-        which = arc4random_uniform(bestcount);
+        bestcount = 0;
         while (getline(&line, &linesize, f) != -1) {
+                linenum++;
                 if (!parse_prime(linenum, line, &dhg))
                         continue;
                 if ((dhg.size > max || dhg.size < min) ||
                     dhg.size != best ||
-                    linenum++ != which) {
+                    bestcount++ != which) {
                         BN_clear_free(dhg.g);
                         BN_clear_free(dhg.p);
                         continue;
@@ -206,9 +208,9 @@ choose_dh(int min, int wantbits, int max)
         free(line);
         line = NULL;
         fclose(f);
-        if (linenum != which+1) {
-                logit("WARNING: line %d disappeared in %s, giving up",
-                    which, _PATH_DH_MODULI);
+        if (bestcount != which + 1) {
+                logit("WARNING: selected prime disappeared in %s, giving up",
+                    _PATH_DH_MODULI);
                 return (dh_new_group_fallback(max));
         }