Merge pull request #611 from besser82/topic/besser82/json-c-0.12/CVE-2020-12762

json-c-0.12.x: Fix CVE-2020-12762 - json-c through 0.14 has an integer overflow and out-of-bounds write ...

README

@@ -24,6 +24,7 @@ Github repo for json-c:
 Then 
 
     $ ./configure
+    $ touch aclocal.m4 Makefile.in   # hack around automake dependencies
     $ make
     $ make install
 

json_object.c

@@ -552,6 +552,7 @@ int64_t json_object_get_int64(struct json_object *jso)
     return jso->o.c_boolean;
   case json_type_string:
 	if (json_parse_int64(jso->o.c_string.str, &cint) == 0) return cint;
+	// fallthrough
   default:
     return 0;
   }

json_tokener.c

@@ -305,6 +305,7 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
             tok->err = json_tokener_error_parse_unexpected;
             goto out;
         }
+	// fallthrough
       case '"':
 	state = json_tokener_state_string;
 	printbuf_reset(tok->pb);
@@ -684,6 +685,7 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
 	    (c == 'i' || c == 'I'))
 	{
 		state = json_tokener_state_inf;
+		tok->st_pos = 0;
 		goto redo_char;
 	}
       }

linkhash.c

@@ -10,6 +10,7 @@
  *
  */
 
+#include <assert.h>
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
@@ -376,17 +377,17 @@ static uint32_t hashlittle( const void *key, size_t length, uint32_t initval)
     /*-------------------------------- last block: affect all 32 bits of (c) */
     switch(length)                   /* all the case statements fall through */
     {
-    case 12: c+=((uint32_t)k[11])<<24;
-    case 11: c+=((uint32_t)k[10])<<16;
-    case 10: c+=((uint32_t)k[9])<<8;
-    case 9 : c+=k[8];
-    case 8 : b+=((uint32_t)k[7])<<24;
-    case 7 : b+=((uint32_t)k[6])<<16;
-    case 6 : b+=((uint32_t)k[5])<<8;
-    case 5 : b+=k[4];
-    case 4 : a+=((uint32_t)k[3])<<24;
-    case 3 : a+=((uint32_t)k[2])<<16;
-    case 2 : a+=((uint32_t)k[1])<<8;
+    case 12: c+=((uint32_t)k[11])<<24; // fallthrough
+    case 11: c+=((uint32_t)k[10])<<16; // fallthrough
+    case 10: c+=((uint32_t)k[9])<<8; // fallthrough
+    case 9 : c+=k[8]; // fallthrough
+    case 8 : b+=((uint32_t)k[7])<<24; // fallthrough
+    case 7 : b+=((uint32_t)k[6])<<16; // fallthrough
+    case 6 : b+=((uint32_t)k[5])<<8; // fallthrough
+    case 5 : b+=k[4]; // fallthrough
+    case 4 : a+=((uint32_t)k[3])<<24; // fallthrough
+    case 3 : a+=((uint32_t)k[2])<<16; // fallthrough
+    case 2 : a+=((uint32_t)k[1])<<8; // fallthrough
     case 1 : a+=k[0];
              break;
     case 0 : return c;
@@ -431,6 +432,8 @@ struct lh_table* lh_table_new(int size, const char *name,
 	int i;
 	struct lh_table *t;
 
+	/* Allocate space for elements to avoid divisions by zero. */
+	assert(size > 0);
 	t = (struct lh_table*)calloc(1, sizeof(struct lh_table));
 	if(!t) lh_abort("lh_table_new: calloc failed\n");
 	t->count = 0;
@@ -495,7 +498,14 @@ int lh_table_insert(struct lh_table *t, void *k, const void *v)
 	unsigned long h, n;
 
 	t->inserts++;
-	if(t->count >= t->size * LH_LOAD_FACTOR) lh_table_resize(t, t->size * 2);
+	if (t->count >= t->size * LH_LOAD_FACTOR) {
+		/* Avoid signed integer overflow with large tables. */
+		int new_size = (t->size > INT_MAX / 2) ? INT_MAX : (t->size * 2);
+		if (t->size == INT_MAX)
+			return -1;
+
+		lh_table_resize(t, new_size);
+	}
 
 	h = t->hash_fn(k);
 	n = h % t->size;

printbuf.c

@@ -15,6 +15,7 @@
 
 #include "config.h"
 
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -63,7 +64,16 @@ static int printbuf_extend(struct printbuf *p, int min_size)
 	if (p->size >= min_size)
 		return 0;
 
-	new_size = json_max(p->size * 2, min_size + 8);
+	/* Prevent signed integer overflows with large buffers. */
+	if (min_size > INT_MAX - 8)
+		return -1;
+	if (p->size > INT_MAX / 2)
+		new_size =  min_size + 8;
+	else {
+		new_size = p->size * 2;
+		if (new_size < min_size + 8)
+			new_size = min_size + 8;
+	}
 #ifdef PRINTBUF_DEBUG
 	MC_DEBUG("printbuf_memappend: realloc "
 	  "bpos=%d min_size=%d old_size=%d new_size=%d\n",
@@ -78,6 +88,9 @@ static int printbuf_extend(struct printbuf *p, int min_size)
 
 int printbuf_memappend(struct printbuf *p, const char *buf, int size)
 {
+  /* Prevent signed integer overflows with large buffers. */
+  if (size > INT_MAX - p->bpos - 1)
+    return -1;
   if (p->size <= p->bpos + size + 1) {
     if (printbuf_extend(p, p->bpos + size + 1) < 0)
       return -1;
@@ -94,6 +107,9 @@ int printbuf_memset(struct printbuf *pb, int offset, int charvalue, int len)
 
 	if (offset == -1)
 		offset = pb->bpos;
+	/* Prevent signed integer overflows with large buffers. */
+	if (len > INT_MAX - offset)
+		return -1;
 	size_needed = offset + len;
 	if (pb->size < size_needed)
 	{

tests/test4.c

@@ -2,9 +2,11 @@
  * gcc -o utf8 utf8.c -I/home/y/include -L./.libs -ljson
  */
 
-#include <stdio.h>
-#include <string.h>
 #include "config.h"
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "json_inttypes.h"
 #include "json_object.h"
@@ -24,6 +26,30 @@ void print_hex( const char* s)
 	printf("\n");
 }
 
+static void test_lot_of_adds(void);
+static void test_lot_of_adds()
+{
+	int ii;
+	char key[50];
+	json_object *jobj = json_object_new_object();
+	assert(jobj != NULL);
+	for (ii = 0; ii < 500; ii++)
+	{
+		snprintf(key, sizeof(key), "k%d", ii);
+		json_object *iobj = json_object_new_int(ii);
+		assert(iobj != NULL);
+		json_object_object_add(jobj, key, iobj);
+		if (json_object_object_get_ex(jobj, key, &iobj) == FALSE)
+		{
+			fprintf(stderr, "FAILED to add object #%d\n", ii);
+			abort();
+		}
+	}
+	printf("%s\n", json_object_to_json_string(jobj));
+	assert(json_object_object_length(jobj) == 500);
+	json_object_put(jobj);
+}
+
 int main()
 {
 	const char *input = "\"\\ud840\\udd26,\\ud840\\udd27,\\ud800\\udd26,\\ud800\\udd27\"";
@@ -49,5 +75,8 @@ int main()
 		retval = 1;
 	}
 	json_object_put(parse_result);
+
+	test_lot_of_adds();
+
 	return retval;
 }

tests/testReplaceExisting.c

@@ -24,7 +24,7 @@ int main(int argc, char **argv)
 	int orig_count = 0;
 	json_object_object_foreach(my_object, key0, val0)
 	{
-		printf("Key at index %d is [%s]", orig_count, key0);
+		printf("Key at index %d is [%s] %d", orig_count, key0, (val0 == NULL));
 		if (strcmp(key0, "deleteme") == 0)
 		{
 			json_object_object_del(my_object, key0);
@@ -41,7 +41,7 @@ int main(int argc, char **argv)
 	orig_count = 0;
 	json_object_object_foreach(my_object, key, val)
 	{
-		printf("Key at index %d is [%s]\n", orig_count, key);
+		printf("Key at index %d is [%s] %d\n", orig_count, key, (val == NULL));
 		orig_count++;
 		if (strcmp(key, "foo2") != 0)
 			continue;
@@ -56,7 +56,7 @@ int main(int argc, char **argv)
 	int retval = 0;
 	json_object_object_foreach(my_object, key2, val2)
 	{
-		printf("Key at index %d is [%s]\n", new_count, key2);
+		printf("Key at index %d is [%s] %d\n", new_count, key2, (val2 == NULL));
 		new_count++;
 		if (strcmp(key2, "foo2") != 0)
 			continue;

tests/testReplaceExisting.expected

@@ -1,15 +1,15 @@
 ==== delete-in-loop test starting ====
-Key at index 0 is [foo1] (kept)
-Key at index 1 is [foo2] (kept)
-Key at index 2 is [deleteme] (deleted)
-Key at index 3 is [foo3] (kept)
+Key at index 0 is [foo1] 0 (kept)
+Key at index 1 is [foo2] 0 (kept)
+Key at index 2 is [deleteme] 0 (deleted)
+Key at index 3 is [foo3] 0 (kept)
 ==== replace-value first loop starting ====
-Key at index 0 is [foo1]
-Key at index 1 is [foo2]
+Key at index 0 is [foo1] 0
+Key at index 1 is [foo2] 0
 replacing value for key [foo2]
-Key at index 2 is [foo3]
+Key at index 2 is [foo3] 0
 ==== second loop starting ====
-Key at index 0 is [foo1]
-Key at index 1 is [foo2]
+Key at index 0 is [foo1] 0
+Key at index 1 is [foo2] 0
 pointer for key [foo2] does match
-Key at index 2 is [foo3]
+Key at index 2 is [foo3] 0

tests/test_parse.c

@@ -79,6 +79,10 @@ static void test_basic_parse()
 	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
 	json_object_put(new_obj);
 
+	new_obj = json_tokener_parse("{ \"min\": Infinity, \"max\": -Infinity}");
+	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
+	json_object_put(new_obj);
+
 	new_obj = json_tokener_parse("True");
 	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
 	json_object_put(new_obj);
@@ -131,7 +135,7 @@ static void test_basic_parse()
 	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
 	json_object_put(new_obj);
 
-	new_obj = json_tokener_parse("{ \"abc\": 12, \"foo\": \"bar\", \"bool0\": false, \"bool1\": true, \"arr\": [ 1, 2, 3, null, 5 ] }");
+	new_obj = json_tokener_parse("{ \"abc\": 12, \"foo\": \"bar\", \"bool0\": false, \"bool1\": true, \"arr\": [ 1, 2, 3, null, 5 ], \"inf\": Infinity, \"-inf\": -Infinity, \"nan\": NaN, \"def\" : -0.22, \"hij\": 0.31 }");
 	printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
 	json_object_put(new_obj);
 }

tests/test_parse.expected

@@ -11,6 +11,7 @@ new_obj.to_string()=Infinity
 new_obj.to_string()=Infinity
 new_obj.to_string()=-Infinity
 new_obj.to_string()=-Infinity
+new_obj.to_string()={ "min": Infinity, "max": -Infinity }
 new_obj.to_string()=true
 new_obj.to_string()=12
 new_obj.to_string()=12.3
@@ -24,7 +25,7 @@ new_obj.to_string()={ }
 new_obj.to_string()={ "foo": "bar" }
 new_obj.to_string()={ "foo": "bar", "baz": null, "bool0": true }
 new_obj.to_string()={ "foo": [ null, "foo" ] }
-new_obj.to_string()={ "abc": 12, "foo": "bar", "bool0": false, "bool1": true, "arr": [ 1, 2, 3, null, 5 ] }
+new_obj.to_string()={ "abc": 12, "foo": "bar", "bool0": false, "bool1": true, "arr": [ 1, 2, 3, null, 5 ], "inf": Infinity, "-inf": -Infinity, "nan": NaN, "def": -0.22, "hij": 0.31 }
 ==================================
 json_tokener_parse_versbose() OK
 ==================================