Ensure that there is a terminating newline when adding a new entry

to known_hosts.  bz#3529, with git+openssh at limpsquid.nl,
ok deraadt@ markus@

diff --git a/usr.bin/ssh/hostfile.c b/usr.bin/ssh/hostfile.c
index e193d42..47b4ade 100644 (file)
--- a/usr.bin/ssh/hostfile.c
+++ b/usr.bin/ssh/hostfile.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: hostfile.c,v 1.93 2022/01/06 22:02:52 djm Exp $ */
+/* $OpenBSD: hostfile.c,v 1.94 2023/02/09 09:54:11 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -513,9 +513,17 @@ add_host_to_hostfile(const char *filename, const char *host,
        if (key == NULL)
                return 1;       /* XXX ? */
        hostfile_create_user_ssh_dir(filename, 0);
-       f = fopen(filename, "a");
+       f = fopen(filename, "a+");
        if (!f)
                return 0;
+       /* Make sure we have a terminating newline. */
+       if (fseek(f, -1L, SEEK_END) == 0 && fgetc(f) != '\n')
+               if (fputc('\n', f) != '\n') {
+                       error("Failed to add terminating newline to %s: %s",
+                          filename, strerror(errno));
+                       fclose(f);
+                       return 0;
+               }
        success = write_host_entry(f, host, NULL, key, store_hash);
        fclose(f);
        return success;