From: Thomas Markwalder <tmark@isc.org>
Date: Thu, 20 Jun 2019 14:43:10 +0000 (-0400)
Subject: [v4_1_esv_r15_p1] Added fixes for CVE-2018-5733 and CVE-2018-5732
X-Git-Tag: v4_1_esv_r16b1~9
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4584b794bed3b54df1b065db165e0f01696670d1;p=thirdparty%2Fdhcp.git

[v4_1_esv_r15_p1] Added fixes for CVE-2018-5733 and CVE-2018-5732

    modified:   RELNOTES
    modified:   common/options.c
---

diff --git a/RELNOTES b/RELNOTES
index edb258d79..eba2bf6ae 100644
--- a/RELNOTES
+++ b/RELNOTES
@@ -117,6 +117,18 @@ dhcp-users@lists.isc.org.
   Thanks to Peter Lewis for requesting this change.
   [ISC-Bugs 47062]
 
+! Option reference count was not correctly decremented in error path
+  when parsing buffer for options. Reported by Felix Wilhelm, Google
+  Security Team.
+  [ISC-Bugs #47140]
+  CVE: CVE-2018-5733
+
+! Corrected an issue where large sized 'X/x' format options were causing
+  option handling logic to overwrite memory when expanding them to human
+  readable form. Reported by Felix Wilhelm, Google Security Team.
+  [ISC-Bugs #47139]
+  CVE: CVE-2018-5732
+
 			Changes since 4.1-ESV-R15b1
 
 - None
diff --git a/common/options.c b/common/options.c
index a136cd5c5..5b4f17d95 100644
--- a/common/options.c
+++ b/common/options.c
@@ -3,7 +3,7 @@
    DHCP options parsing and reassembly. */
 
 /*
- * Copyright (c) 2004-2017 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2004-2018 by Internet Systems Consortium, Inc. ("ISC")
  * Copyright (c) 1995-2003 by Internet Software Consortium
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -177,6 +177,8 @@ int parse_option_buffer (options, buffer, length, universe)
 
 		/* If the length is outrageous, the options are bad. */
 		if (offset + len > length) {
+			/* Avoid reference count overflow */
+			option_dereference(&option, MDL);
 			reason = "option length exceeds option buffer length";
 		      bogus:
 			log_error("parse_option_buffer: malformed option "
@@ -1751,7 +1753,8 @@ format_min_length(format, oc)
 
 
 /* Format the specified option so that a human can easily read it. */
-
+/* Maximum pretty printed size */
+#define MAX_OUTPUT_SIZE 32*1024
 const char *pretty_print_option (option, data, len, emit_commas, emit_quotes)
 	struct option *option;
 	const unsigned char *data;
@@ -1759,8 +1762,9 @@ const char *pretty_print_option (option, data, len, emit_commas, emit_quotes)
 	int emit_commas;
 	int emit_quotes;
 {
-	static char optbuf [32768]; /* XXX */
-	static char *endbuf = &optbuf[sizeof(optbuf)];
+	/* We add 128 byte pad so we don't have to add checks everywhere. */
+	static char optbuf [MAX_OUTPUT_SIZE + 128]; /* XXX */
+	static char *endbuf = optbuf + MAX_OUTPUT_SIZE;
 	int hunksize = 0;
 	int opthunk = 0;
 	int hunkinc = 0;
@@ -2187,6 +2191,12 @@ const char *pretty_print_option (option, data, len, emit_commas, emit_quotes)
 					   fmtbuf [j]);
 			}
 			op += strlen (op);
+			if (op >= endbuf) {
+				log_error ("Option data exceeds"
+					   " maximum size %d", MAX_OUTPUT_SIZE);
+				return ("<error>");
+			}
+
 			if (dp == data + len)
 				break;
 			if (j + 1 < numelem && comma != ':')