Fix sk_is_sorted to tread 0 and 1 element lists as sorted.

from boringssl

ok tb@ jsing@

1 files changed, 12 insertions, 3 deletions

diff --git a/src/lib/libcrypto/stack/stack.c b/src/lib/libcrypto/stack/stack.c
index bc5b2f6e83..65bd3217d1 100644
--- a/src/lib/libcrypto/stack/stack.c
+++ b/src/lib/libcrypto/stack/stack.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: stack.c,v 1.22 2023/02/16 08:38:17 tb Exp $ */
+/* $OpenBSD: stack.c,v 1.23 2023/04/24 15:35:22 beck Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -356,8 +356,17 @@ LCRYPTO_ALIAS(sk_sort);
 int
 sk_is_sorted(const _STACK *st)
 {
-        if (!st)
+        if (st == NULL)
+                return 1;
+
+        if (st->sorted)
                 return 1;
-        return st->sorted;
+
+        /* If there is no comparison function we cannot sort. */
+        if (st->comp == NULL)
+                return 0;
+
+        /* Lists with zero or one elements are always sorted. */
+        return st->num <= 1;
 }
 LCRYPTO_ALIAS(sk_is_sorted);