From fabf4cd14108a60d9486f38ae58694d615592bc9 Mon Sep 17 00:00:00 2001
From: Darren Tucker <dtucker@dtucker.net>
Date: Tue, 7 Oct 2025 21:07:05 +1100
Subject: [PATCH 6/6] Use calloc for sshkeys if mmap is not supported.

Based on Github PR#597 from Mike Frysinger, any bugs added by me.
---
 configure.ac | 2 ++
 sshkey.c     | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/configure.ac b/configure.ac
index 3eb6d4697..98f2e3e1c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -536,6 +536,7 @@ AC_CHECK_HEADERS([ \
     nlist.h \
     poll.h \
     stdint.h \
+    sys/mmap.h \
     sys/stat.h \
     sys/time.h \
     sys/un.h \
@@ -2103,6 +2104,7 @@ AC_CHECK_FUNCS([ \
 	memmove \
 	memset_s \
 	mkdtemp \
+	mmap \
 	ngetaddrinfo \
 	nlist \
 	nsleep \
diff --git a/sshkey.c b/sshkey.c
index e17e929e0..206b72921 100644
--- a/sshkey.c
+++ b/sshkey.c
@@ -723,6 +723,7 @@ sshkey_sk_cleanup(struct sshkey *k)
 static int
 sshkey_prekey_alloc(u_char **prekeyp, size_t len)
 {
+#if defined(HAVE_MMAP) && defined(MAP_ANON) && defined(MAP_PRIVATE)
 	u_char *prekey;
 
 	*prekeyp = NULL;
@@ -734,14 +735,21 @@ sshkey_prekey_alloc(u_char **prekeyp, size_t len)
 #endif
 	*prekeyp = prekey;
 	return 0;
+#else
+	*prekeyp = calloc(1, len);
+#endif /* HAVE_MMAP et al */
 }
 
 static void
 sshkey_prekey_free(void *prekey, size_t len)
 {
+#if defined(HAVE_MMAP) && defined(MAP_ANON) && defined(MAP_PRIVATE)
 	if (prekey == NULL)
 		return;
 	munmap(prekey, len);
+#else
+	free(prekey);
+#endif /* HAVE_MMAP et al */
 }
 
 static void
-- 
2.51.0