From 6b9716ca5aa1bfe44c0d1ad7030446b28b4f9f84 Mon Sep 17 00:00:00 2001
From: Stepan Broz <sbroz@redhat.com>
Date: Mon, 25 Sep 2023 12:41:54 +0200
Subject: [PATCH 1/1] Backport of CVE-2023-3341 fix

Taken from BIND 9.16.44 change.
---
 lib/isccc/cc.c                   | 36 +++++++++++++++++++++++---------
 lib/isccc/include/isccc/result.h |  4 +++-
 lib/isccc/result.c               |  4 +++-
 3 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/lib/isccc/cc.c b/lib/isccc/cc.c
index 42b3046..7f67d70 100644
--- a/lib/isccc/cc.c
+++ b/lib/isccc/cc.c
@@ -51,6 +51,10 @@
 
 #define MAX_TAGS		256
 #define DUP_LIFETIME		900
+#ifndef ISCCC_MAXDEPTH
+#define ISCCC_MAXDEPTH \
+	10 /* Big enough for rndc which just sends a string each way. */
+#endif
 
 typedef isccc_sexpr_t *sexpr_ptr;
 
@@ -571,19 +575,23 @@ verify(isccc_sexpr_t *alist, unsigned char *data, unsigned int length,
 
 static isc_result_t
 table_fromwire(isccc_region_t *source, isccc_region_t *secret,
-	       isc_uint32_t algorithm, isccc_sexpr_t **alistp);
+	       isc_uint32_t algorithm, unsigned int depth, isccc_sexpr_t **alistp);
 
 static isc_result_t
-list_fromwire(isccc_region_t *source, isccc_sexpr_t **listp);
+list_fromwire(isccc_region_t *source, unsigned int depth, isccc_sexpr_t **listp);
 
 static isc_result_t
-value_fromwire(isccc_region_t *source, isccc_sexpr_t **valuep) {
+value_fromwire(isccc_region_t *source, unsigned int depth, isccc_sexpr_t **valuep) {
 	unsigned int msgtype;
 	isc_uint32_t len;
 	isccc_sexpr_t *value;
 	isccc_region_t active;
 	isc_result_t result;
 
+	if (depth > ISCCC_MAXDEPTH) {
+		return (ISCCC_R_MAXDEPTH);
+	}
+
 	if (REGION_SIZE(*source) < 1 + 4)
 		return (ISC_R_UNEXPECTEDEND);
 	GET8(msgtype, source->rstart);
@@ -601,9 +609,9 @@ value_fromwire(isccc_region_t *source, isccc_sexpr_t **valuep) {
 		} else
 			result = ISC_R_NOMEMORY;
 	} else if (msgtype == ISCCC_CCMSGTYPE_TABLE)
-		result = table_fromwire(&active, NULL, 0, valuep);
+		result = table_fromwire(&active, NULL, 0, depth + 1, valuep);
 	else if (msgtype == ISCCC_CCMSGTYPE_LIST)
-		result = list_fromwire(&active, valuep);
+		result = list_fromwire(&active, depth + 1, valuep);
 	else
 		result = ISCCC_R_SYNTAX;
 
@@ -612,7 +620,7 @@ value_fromwire(isccc_region_t *source, isccc_sexpr_t **valuep) {
 
 static isc_result_t
 table_fromwire(isccc_region_t *source, isccc_region_t *secret,
-	       isc_uint32_t algorithm, isccc_sexpr_t **alistp)
+	       isc_uint32_t algorithm, unsigned int depth, isccc_sexpr_t **alistp)
 {
 	char key[256];
 	isc_uint32_t len;
@@ -623,6 +631,10 @@ table_fromwire(isccc_region_t *source, isccc_region_t *secret,
 
 	REQUIRE(alistp != NULL && *alistp == NULL);
 
+	if (depth > ISCCC_MAXDEPTH) {
+		return (ISCCC_R_MAXDEPTH);
+	}
+
 	checksum_rstart = NULL;
 	first_tag = ISC_TRUE;
 	alist = isccc_alist_create();
@@ -638,7 +650,7 @@ table_fromwire(isccc_region_t *source, isccc_region_t *secret,
 		GET_MEM(key, len, source->rstart);
 		key[len] = '\0';	/* Ensure NUL termination. */
 		value = NULL;
-		result = value_fromwire(source, &value);
+		result = value_fromwire(source, depth + 1, &value);
 		if (result != ISC_R_SUCCESS)
 			goto bad;
 		if (isccc_alist_define(alist, key, value) == NULL) {
@@ -671,14 +683,18 @@ table_fromwire(isccc_region_t *source, isccc_region_t *secret,
 }
 
 static isc_result_t
-list_fromwire(isccc_region_t *source, isccc_sexpr_t **listp) {
+list_fromwire(isccc_region_t *source, unsigned int depth, isccc_sexpr_t **listp) {
 	isccc_sexpr_t *list, *value;
 	isc_result_t result;
 
+	if (depth > ISCCC_MAXDEPTH) {
+		return (ISCCC_R_MAXDEPTH);
+	}
+
 	list = NULL;
 	while (!REGION_EMPTY(*source)) {
 		value = NULL;
-		result = value_fromwire(source, &value);
+		result = value_fromwire(source, depth + 1, &value);
 		if (result != ISC_R_SUCCESS) {
 			isccc_sexpr_free(&list);
 			return (result);
@@ -709,7 +725,7 @@ isccc_cc_fromwire(isccc_region_t *source, isccc_sexpr_t **alistp,
 	if (version != 1)
 		return (ISCCC_R_UNKNOWNVERSION);
 
-	return (table_fromwire(source, secret, algorithm, alistp));
+	return (table_fromwire(source, secret, algorithm, 0, alistp));
 }
 
 static isc_result_t
diff --git a/lib/isccc/include/isccc/result.h b/lib/isccc/include/isccc/result.h
index 6ff81ad..3e14ee0 100644
--- a/lib/isccc/include/isccc/result.h
+++ b/lib/isccc/include/isccc/result.h
@@ -47,8 +47,10 @@
 #define ISCCC_R_CLOCKSKEW		(ISC_RESULTCLASS_ISCCC + 4)
 /*% Duplicate */
 #define ISCCC_R_DUPLICATE		(ISC_RESULTCLASS_ISCCC + 5)
+/*% Maximum recursion depth */
+#define ISCCC_R_MAXDEPTH               (ISC_RESULTCLASS_ISCCC + 6)
 
-#define ISCCC_R_NRESULTS 		6	/*%< Number of results */
+#define ISCCC_R_NRESULTS 		7	/*%< Number of results */
 
 ISC_LANG_BEGINDECLS
 
diff --git a/lib/isccc/result.c b/lib/isccc/result.c
index 75f5ade..91df50a 100644
--- a/lib/isccc/result.c
+++ b/lib/isccc/result.c
@@ -40,7 +40,8 @@ static const char *text[ISCCC_R_NRESULTS] = {
 	"bad auth",				/* 3 */
 	"expired",				/* 4 */
 	"clock skew",				/* 5 */
-	"duplicate"				/* 6 */
+	"duplicate",				/* 6 */
+	"max depth",				/* 7 */
 };
 
 static const char *ids[ISCCC_R_NRESULTS] = {
@@ -50,6 +51,7 @@ static const char *ids[ISCCC_R_NRESULTS] = {
 	"ISCCC_R_EXPIRED",
 	"ISCCC_R_CLOCKSKEW",
 	"ISCCC_R_DUPLICATE",
+	"ISCCC_R_MAXDEPTH",
 };
 
 #define ISCCC_RESULT_RESULTSET			2
-- 
2.41.0