upstream: Plug mem leaks on error paths, based in part on github

pr#120 from David Carlier.  ok djm@.

OpenBSD-Commit-ID: c57adeb1022a8148fc86e5a88837b3b156dbdb7e

1 files changed, 19 insertions, 15 deletions

diff --git a/ssh_api.c b/ssh_api.c
index 6ea40b5e7..03dac0982 100644
--- a/ssh_api.c
+++ b/ssh_api.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh_api.c,v 1.17 2019/09/06 05:23:55 djm Exp $ */
+/* $OpenBSD: ssh_api.c,v 1.18 2019/09/13 04:36:43 dtucker Exp $ */
 /*
  * Copyright (c) 2012 Markus Friedl.  All rights reserved.
  *
@@ -330,8 +330,8 @@ _ssh_read_banner(struct ssh *ssh, struct sshbuf *banner)
         const char *mismatch = "Protocol mismatch.\r\n";
         const u_char *s = sshbuf_ptr(input);
         u_char c;
-        char *cp, *remote_version;
-        int r, remote_major, remote_minor, expect_nl;
+        char *cp = NULL, *remote_version = NULL;
+        int r = 0, remote_major, remote_minor, expect_nl;
         size_t n, j;
 
         for (j = n = 0;;) {
@@ -357,10 +357,8 @@ _ssh_read_banner(struct ssh *ssh, struct sshbuf *banner)
                 if (sshbuf_len(banner) >= 4 &&
                     memcmp(sshbuf_ptr(banner), "SSH-", 4) == 0)
                         break;
-                if ((cp = sshbuf_dup_string(banner)) == NULL)
-                        return SSH_ERR_ALLOC_FAIL;
-                debug("%s: %s", __func__, cp);
-                free(cp);
+                debug("%s: %.*s", __func__, (int)sshbuf_len(banner),
+                    sshbuf_ptr(banner));
                 /* Accept lines before banner only on client */
                 if (ssh->kex->server || ++n > SSH_MAX_PRE_BANNER_LINES) {
   bad:
@@ -373,19 +371,22 @@ _ssh_read_banner(struct ssh *ssh, struct sshbuf *banner)
         if ((r = sshbuf_consume(input, j)) != 0)
                 return r;
 
-        if ((cp = sshbuf_dup_string(banner)) == NULL)
-                return SSH_ERR_ALLOC_FAIL;
         /* XXX remote version must be the same size as banner for sscanf */
-        if ((remote_version = calloc(1, sshbuf_len(banner))) == NULL)
-                return SSH_ERR_ALLOC_FAIL;
+        if ((cp = sshbuf_dup_string(banner)) == NULL ||
+            (remote_version = calloc(1, sshbuf_len(banner))) == NULL) {
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
 
         /*
          * Check that the versions match.  In future this might accept
          * several versions and set appropriate flags to handle them.
          */
         if (sscanf(cp, "SSH-%d.%d-%[^\n]\n",
-            &remote_major, &remote_minor, remote_version) != 3)
-                return SSH_ERR_INVALID_FORMAT;
+            &remote_major, &remote_minor, remote_version) != 3) {
+                r = SSH_ERR_INVALID_FORMAT;
+                goto out;
+        }
         debug("Remote protocol version %d.%d, remote software version %.100s",
             remote_major, remote_minor, remote_version);
 
@@ -395,10 +396,13 @@ _ssh_read_banner(struct ssh *ssh, struct sshbuf *banner)
                 remote_minor = 0;
         }
         if (remote_major != 2)
-                return SSH_ERR_PROTOCOL_MISMATCH;
+                r = SSH_ERR_PROTOCOL_MISMATCH;
+
         debug("Remote version string %.100s", cp);
+ out:
         free(cp);
-        return 0;
+        free(remote_version);
+        return r;
 }
 
 /* Send our own protocol version identification. */