upstream: f sshpkt functions fail, then password is not cleared

with freezero. Unconditionally call freezero to guarantee that password is
removed from RAM.

From tobias@ and c3h2_ctf via github PR#286, ok djm@

OpenBSD-Commit-ID: 6b093619c9515328e25b0f8093779c52402c89cd

diff --git a/auth2-passwd.c b/auth2-passwd.c
index f8a6dbc193957c99f653647a7a07f677002b833a..cc12cfbc1f1ae30aacd4accd9f16857375f8cbc2 100644 (file)
--- a/auth2-passwd.c
+++ b/auth2-passwd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-passwd.c,v 1.20 2021/12/19 22:12:07 djm Exp $ */
+/* $OpenBSD: auth2-passwd.c,v 1.21 2022/05/27 04:29:40 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -51,16 +51,18 @@ extern ServerOptions options;
 static int
 userauth_passwd(struct ssh *ssh, const char *method)
 {
-       char *password;
+       char *password = NULL;
        int authenticated = 0, r;
        u_char change;
-       size_t len;
+       size_t len = 0;
 
        if ((r = sshpkt_get_u8(ssh, &change)) != 0 ||
            (r = sshpkt_get_cstring(ssh, &password, &len)) != 0 ||
            (change && (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0) ||
-           (r = sshpkt_get_end(ssh)) != 0)
+           (r = sshpkt_get_end(ssh)) != 0) {
+               freezero(password, len);
                fatal_fr(r, "parse packet");
+       }
 
        if (change)
                logit("password change not supported");