upstream: revert compat.[ch] section of the following change. It

causes double-free under some circumstances.

--

date: 2018/07/31 03:07:24;  author: djm;  state: Exp;  lines: +33 -18;  commitid: f7g4UI8eeOXReTPh;
fix some memory leaks spotted by Coverity via Jakub Jelen in bz#2366
feedback and ok dtucker@

OpenBSD-Commit-ID: 1e77547f60fdb5e2ffe23e2e4733c54d8d2d1137

4 files changed, 34 insertions, 56 deletions

diff --git a/compat.c b/compat.c
index 563e13331..0624dc6de 100644
--- a/compat.c
+++ b/compat.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: compat.c,v 1.112 2018/07/31 03:07:24 djm Exp $ */
+/* $OpenBSD: compat.c,v 1.113 2018/08/13 02:41:05 djm Exp $ */
 /*
  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  *
@@ -184,17 +184,13 @@ proto_spec(const char *spec)
 }
 
 char *
-compat_cipher_proposal(char *cipher_prop, u_int compat)
+compat_cipher_proposal(char *cipher_prop)
 {
-        char *cp;
-
-        if (!(compat & SSH_BUG_BIGENDIANAES))
+        if (!(datafellows & SSH_BUG_BIGENDIANAES))
                 return cipher_prop;
         debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
-        if ((cp = match_filter_blacklist(cipher_prop, "aes*")) == NULL)
+        if ((cipher_prop = match_filter_blacklist(cipher_prop, "aes*")) == NULL)
                 fatal("match_filter_blacklist failed");
-        free(cipher_prop);
-        cipher_prop = cp;
         debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
         if (*cipher_prop == '\0')
                 fatal("No supported ciphers found");
@@ -202,17 +198,13 @@ compat_cipher_proposal(char *cipher_prop, u_int compat)
 }
 
 char *
-compat_pkalg_proposal(char *pkalg_prop, u_int compat)
+compat_pkalg_proposal(char *pkalg_prop)
 {
-        char *cp;
-
-        if (!(compat & SSH_BUG_RSASIGMD5))
+        if (!(datafellows & SSH_BUG_RSASIGMD5))
                 return pkalg_prop;
         debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
-        if ((cp = match_filter_blacklist(pkalg_prop, "ssh-rsa")) == NULL)
+        if ((pkalg_prop = match_filter_blacklist(pkalg_prop, "ssh-rsa")) == NULL)
                 fatal("match_filter_blacklist failed");
-        free(pkalg_prop);
-        pkalg_prop = cp;
         debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
         if (*pkalg_prop == '\0')
                 fatal("No supported PK algorithms found");
@@ -220,31 +212,24 @@ compat_pkalg_proposal(char *pkalg_prop, u_int compat)
 }
 
 char *
-compat_kex_proposal(char *kex_prop, u_int compat)
+compat_kex_proposal(char *p)
 {
-        char *cp;
-
-        if ((compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
-                return kex_prop;
-        debug2("%s: original KEX proposal: %s", __func__, kex_prop);
-        if ((compat & SSH_BUG_CURVE25519PAD) != 0) {
-                if ((cp = match_filter_blacklist(kex_prop,
+        if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
+                return p;
+        debug2("%s: original KEX proposal: %s", __func__, p);
+        if ((datafellows & SSH_BUG_CURVE25519PAD) != 0)
+                if ((p = match_filter_blacklist(p,
                     "curve25519-sha256@libssh.org")) == NULL)
                         fatal("match_filter_blacklist failed");
-                free(kex_prop);
-                kex_prop = cp;
-        }
-        if ((compat & SSH_OLD_DHGEX) != 0) {
-                if ((cp = match_filter_blacklist(kex_prop,
+        if ((datafellows & SSH_OLD_DHGEX) != 0) {
+                if ((p = match_filter_blacklist(p,
                     "diffie-hellman-group-exchange-sha256,"
                     "diffie-hellman-group-exchange-sha1")) == NULL)
                         fatal("match_filter_blacklist failed");
-                free(kex_prop);
-                kex_prop = cp;
         }
-        debug2("%s: compat KEX proposal: %s", __func__, kex_prop);
-        if (*kex_prop == '\0')
+        debug2("%s: compat KEX proposal: %s", __func__, p);
+        if (*p == '\0')
                 fatal("No supported key exchange algorithms found");
-        return kex_prop;
+        return p;
 }
 
diff --git a/compat.h b/compat.h
index e2877737b..d611d33e7 100644
--- a/compat.h
+++ b/compat.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: compat.h,v 1.53 2018/07/31 03:07:24 djm Exp $ */
+/* $OpenBSD: compat.h,v 1.54 2018/08/13 02:41:05 djm Exp $ */
 
 /*
  * Copyright (c) 1999, 2000, 2001 Markus Friedl.  All rights reserved.
@@ -65,15 +65,9 @@
 
 u_int    compat_datafellows(const char *);
 int      proto_spec(const char *);
-
-/*
- * compat_*_proposal will update their respective proposals based on the
- * active compat flags. The replacement is performed in-place - i.e. they
- * will free their argument and return a new heap-allocated string.
- */
-char    *compat_cipher_proposal(char *, u_int compat);
-char    *compat_pkalg_proposal(char *, u_int compat);
-char    *compat_kex_proposal(char *, u_int compat);
+char    *compat_cipher_proposal(char *);
+char    *compat_pkalg_proposal(char *);
+char    *compat_kex_proposal(char *);
 
 extern int datafellows;
 #endif
diff --git a/sshconnect2.c b/sshconnect2.c
index 93192d186..10e4f0a08 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect2.c,v 1.283 2018/07/31 03:07:24 djm Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.284 2018/08/13 02:41:05 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
@@ -167,11 +167,11 @@ ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 
         if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
                 fatal("%s: kex_names_cat", __func__);
-        myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s, datafellows);
+        myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
         myproposal[PROPOSAL_ENC_ALGS_CTOS] =
-            compat_cipher_proposal(options.ciphers, datafellows);
+            compat_cipher_proposal(options.ciphers);
         myproposal[PROPOSAL_ENC_ALGS_STOC] =
-            compat_cipher_proposal(options.ciphers, datafellows);
+            compat_cipher_proposal(options.ciphers);
         myproposal[PROPOSAL_COMP_ALGS_CTOS] =
             myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ?
             "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib";
@@ -184,15 +184,14 @@ ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
                         fatal("%s: kex_assemble_namelist", __func__);
                 free(all_key);
                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
-                    compat_pkalg_proposal(options.hostkeyalgorithms,
-                    datafellows);
+                    compat_pkalg_proposal(options.hostkeyalgorithms);
         } else {
                 /* Enforce default */
                 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG);
                 /* Prefer algorithms that we already have keys for */
                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
                     compat_pkalg_proposal(
-                    order_hostkeyalgs(host, hostaddr, port), datafellows);
+                    order_hostkeyalgs(host, hostaddr, port));
         }
 
         if (options.rekey_limit || options.rekey_interval)
@@ -224,7 +223,7 @@ ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 
         /* remove ext-info from the KEX proposals for rekeying */
         myproposal[PROPOSAL_KEX_ALGS] =
-            compat_kex_proposal(options.kex_algorithms, datafellows);
+            compat_kex_proposal(options.kex_algorithms);
         if ((r = kex_prop2buf(kex->my, myproposal)) != 0)
                 fatal("kex_prop2buf: %s", ssh_err(r));
 
diff --git a/sshd.c b/sshd.c
index d3bd8fdaa..a738c3ab6 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.513 2018/07/31 03:07:24 djm Exp $ */
+/* $OpenBSD: sshd.c,v 1.514 2018/08/13 02:41:05 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2268,11 +2268,11 @@ do_ssh2_kex(void)
         int r;
 
         myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
-            options.kex_algorithms, datafellows);
+            options.kex_algorithms);
         myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
-            options.ciphers, datafellows);
+            options.ciphers);
         myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
-            options.ciphers, datafellows);
+            options.ciphers);
         myproposal[PROPOSAL_MAC_ALGS_CTOS] =
             myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
 
@@ -2286,7 +2286,7 @@ do_ssh2_kex(void)
                     options.rekey_interval);
 
         myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
-            list_hostkey_types(), datafellows);
+            list_hostkey_types());
 
         /* start key exchange */
         if ((r = kex_setup(active_state, myproposal)) != 0)