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Fix #880 Max recursion depth for cJSON_Duplicate to prevent stack exhaustion #888

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Fix #880 Max recursion depth for cJSON_Duplicate to prevent stack exhaustion #888

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0719f72
Added max recusrion depth for cJSONDuplicate to prevent stack exhaust…
vwvw Aug 30, 2024
4525479
Wrong counter increment
vwvw Aug 30, 2024
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12 changes: 11 additions & 1 deletion cJSON.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2726,7 +2726,14 @@ CJSON_PUBLIC(cJSON *) cJSON_CreateStringArray(const char *const *strings, int co
}

/* Duplication */
cJSON * cJSON_Duplicate_rec(const cJSON *item, size_t depth, cJSON_bool recurse);

CJSON_PUBLIC(cJSON *) cJSON_Duplicate(const cJSON *item, cJSON_bool recurse)
{
return cJSON_Duplicate_rec(item, 0, recurse );
}

cJSON * cJSON_Duplicate_rec(const cJSON *item, size_t depth, cJSON_bool recurse)
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{
cJSON *newitem = NULL;
cJSON *child = NULL;
Expand Down Expand Up @@ -2773,7 +2780,10 @@ CJSON_PUBLIC(cJSON *) cJSON_Duplicate(const cJSON *item, cJSON_bool recurse)
child = item->child;
while (child != NULL)
{
newchild = cJSON_Duplicate(child, true); /* Duplicate (with recurse) each item in the ->next chain */
if(depth >= CJSON_CIRCULAR_LIMIT) {
goto fail;
}
newchild = cJSON_Duplicate_rec(child, depth + 1, true); /* Duplicate (with recurse) each item in the ->next chain */
if (!newchild)
{
goto fail;
Expand Down
6 changes: 6 additions & 0 deletions cJSON.h
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Expand Up @@ -137,6 +137,12 @@ typedef int cJSON_bool;
#define CJSON_NESTING_LIMIT 1000
#endif

/* Limits the length of circular references can be before cJSON rejects to parse them.
* This is to prevent stack overflows. */
#ifndef CJSON_CIRCULAR_LIMIT
#define CJSON_CIRCULAR_LIMIT 10000
#endif

/* returns the version of cJSON as a string */
CJSON_PUBLIC(const char*) cJSON_Version(void);

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18 changes: 18 additions & 0 deletions tests/misc_tests.c
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Expand Up @@ -219,6 +219,23 @@ static void cjson_should_not_parse_to_deeply_nested_jsons(void)
TEST_ASSERT_NULL_MESSAGE(cJSON_Parse(deep_json), "To deep JSONs should not be parsed.");
}

static void cjson_should_not_follow_too_deep_circular_references(void)
{
cJSON *o = cJSON_CreateArray();
cJSON *a = cJSON_CreateArray();
cJSON *b = cJSON_CreateArray();
cJSON *x;

cJSON_AddItemToArray(o, a);
cJSON_AddItemToArray(a, b);
cJSON_AddItemToArray(b, o);

x = cJSON_Duplicate(o, 1);
TEST_ASSERT_NULL(x);
cJSON_DetachItemFromArray(b, 0);
cJSON_Delete(o);
}

static void cjson_set_number_value_should_set_numbers(void)
{
cJSON number[1] = {{NULL, NULL, NULL, cJSON_Number, NULL, 0, 0, NULL}};
Expand Down Expand Up @@ -744,6 +761,7 @@ int CJSON_CDECL main(void)
RUN_TEST(cjson_get_object_item_case_sensitive_should_not_crash_with_array);
RUN_TEST(typecheck_functions_should_check_type);
RUN_TEST(cjson_should_not_parse_to_deeply_nested_jsons);
RUN_TEST(cjson_should_not_follow_too_deep_circular_references);
RUN_TEST(cjson_set_number_value_should_set_numbers);
RUN_TEST(cjson_detach_item_via_pointer_should_detach_items);
RUN_TEST(cjson_replace_item_via_pointer_should_replace_items);
Expand Down
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