Don't leak the strings allocated by order_hostkeyalgs() and

list_hostkey_types() that are passed to compat_pkalg_proposal().
Part of github PR#324 from ZoltanFridrich, ok djm@

This is a roll-forward of the previous rollback now that the required
changes in compat.c have been done.

diff --git a/usr.bin/ssh/sshconnect2.c b/usr.bin/ssh/sshconnect2.c
index cd0a4e8..67f8e03 100644 (file)
--- a/usr.bin/ssh/sshconnect2.c
+++ b/usr.bin/ssh/sshconnect2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect2.c,v 1.358 2022/06/24 10:45:06 dtucker Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.359 2022/07/01 03:39:44 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
@@ -213,6 +213,7 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port,
 {
        char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
        char *s, *all_key;
+       char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL;
        int r, use_known_hosts_order = 0;
 
        xxx_host = host;
@@ -238,10 +239,9 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port,
 
        if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
                fatal_f("kex_names_cat");
-       myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(ssh, s);
+       myproposal[PROPOSAL_KEX_ALGS] = prop_kex = compat_kex_proposal(ssh, s);
        myproposal[PROPOSAL_ENC_ALGS_CTOS] =
-           compat_cipher_proposal(ssh, options.ciphers);
-       myproposal[PROPOSAL_ENC_ALGS_STOC] =
+           myproposal[PROPOSAL_ENC_ALGS_STOC] = prop_enc =
            compat_cipher_proposal(ssh, options.ciphers);
        myproposal[PROPOSAL_COMP_ALGS_CTOS] =
            myproposal[PROPOSAL_COMP_ALGS_STOC] =
@@ -250,12 +250,12 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port,
            myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
        if (use_known_hosts_order) {
                /* Query known_hosts and prefer algorithms that appear there */
-               myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
+               myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey =
                    compat_pkalg_proposal(ssh,
                    order_hostkeyalgs(host, hostaddr, port, cinfo));
        } else {
                /* Use specified HostkeyAlgorithms exactly */
-               myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
+               myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey =
                    compat_pkalg_proposal(ssh, options.hostkeyalgorithms);
        }
 
@@ -296,6 +296,10 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port,
            (r = ssh_packet_write_wait(ssh)) != 0)
                fatal_fr(r, "send packet");
 #endif
+       /* Free only parts of proposal that were dynamically allocated here. */
+       free(prop_kex);
+       free(prop_enc);
+       free(prop_hostkey);
 }
 
 /*

diff --git a/usr.bin/ssh/sshd.c b/usr.bin/ssh/sshd.c
index 16a5e4f..dc45091 100644 (file)
--- a/usr.bin/ssh/sshd.c
+++ b/usr.bin/ssh/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.588 2022/06/24 10:45:06 dtucker Exp $ */
+/* $OpenBSD: sshd.c,v 1.589 2022/07/01 03:39:44 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2195,12 +2195,14 @@ do_ssh2_kex(struct ssh *ssh)
 {
        char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
        struct kex *kex;
+       char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL;
        int r;
 
-       myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(ssh,
+       myproposal[PROPOSAL_KEX_ALGS] = prop_kex = compat_kex_proposal(ssh,
            options.kex_algorithms);
-       myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(ssh,
-           options.ciphers);
+       myproposal[PROPOSAL_ENC_ALGS_CTOS] =
+           myproposal[PROPOSAL_ENC_ALGS_STOC] = prop_enc =
+           compat_cipher_proposal(ssh, options.ciphers);
        myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(ssh,
            options.ciphers);
        myproposal[PROPOSAL_MAC_ALGS_CTOS] =
@@ -2215,8 +2217,8 @@ do_ssh2_kex(struct ssh *ssh)
                ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
                    options.rekey_interval);
 
-       myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
-           ssh, list_hostkey_types());
+       myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey =
+          compat_pkalg_proposal(ssh, list_hostkey_types());
 
        /* start key exchange */
        if ((r = kex_setup(ssh, myproposal)) != 0)
@@ -2249,6 +2251,9 @@ do_ssh2_kex(struct ssh *ssh)
            (r = ssh_packet_write_wait(ssh)) != 0)
                fatal_fr(r, "send test");
 #endif
+       free(prop_kex);
+       free(prop_enc);
+       free(prop_hostkey);
        debug("KEX done");
 }