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variant_utils: tighten MessagePack nesting limit #94

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Merged
edsiper merged 1 commit into from
Jul 21, 2026
Merged

variant_utils: tighten MessagePack nesting limit #94

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14 changes: 9 additions & 5 deletions include/ctraces/ctr_variant_utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@
#define CFL_VARIANT_UTILS_INITIAL_ARRAY_SIZE 100
#define CFL_VARIANT_UTILS_SERIALIZED_ARRAY_SIZE_LIMIT 100000
#define CFL_VARIANT_UTILS_SERIALIZED_MAP_SIZE_LIMIT 100000
#define CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH 64
#define CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH 32
#define CFL_VARIANT_UTILS_MAXIMUM_KEY_LENGTH (1024 * 1000)

/* These are the only functions meant for general use,
Expand Down Expand Up @@ -246,6 +246,10 @@ static inline int unpack_cfl_array_depth(mpack_reader_t *reader,
size_t index;
mpack_tag_t tag;

if (depth >= CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH) {
return -2;
}

result = unpack_cfl_variant_read_tag(reader, &tag, mpack_type_array);

if (result != 0) {
Expand Down Expand Up @@ -318,6 +322,10 @@ static inline int unpack_cfl_kvlist_depth(mpack_reader_t *reader,
size_t index;
mpack_tag_t tag;

if (depth >= CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH) {
return -2;
}

result = unpack_cfl_variant_read_tag(reader, &tag, mpack_type_map);

if (result != 0) {
Expand Down Expand Up @@ -670,10 +678,6 @@ static inline int unpack_cfl_variant_depth(mpack_reader_t *reader,
int result;
mpack_tag_t tag;

if (depth >= CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH) {
return -1;
}

tag = mpack_peek_tag(reader);

if (mpack_ok != mpack_reader_error(reader)) {
Expand Down
59 changes: 51 additions & 8 deletions tests/decoding.c
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Original file line number Diff line number Diff line change
Expand Up @@ -716,32 +716,75 @@ void test_msgpack_long_attribute_key()
ctr_destroy(ctx);
}

void test_msgpack_variant_limits()
static void check_variant_nesting_limit(int use_maps, size_t nesting_depth,
int expected_result)
{
char *buffer;
size_t size;
int index;
size_t index;
int result;
mpack_writer_t writer;
mpack_reader_t reader;
struct cfl_variant *variant;
struct cfl_kvlist *kvlist;

buffer = NULL;
size = 0;
variant = NULL;
mpack_writer_init_growable(&writer, &buffer, &size);
for (index = 0; index < CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH + 1; index++) {
mpack_start_array(&writer, 1);

for (index = 0; index < nesting_depth; index++) {
if (use_maps) {
mpack_start_map(&writer, 1);
mpack_write_cstr(&writer, "key");
}
else {
mpack_start_array(&writer, 1);
}
}

mpack_write_i64(&writer, 1);
for (index = 0; index < CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH + 1; index++) {
mpack_finish_array(&writer);

for (index = 0; index < nesting_depth; index++) {
if (use_maps) {
mpack_finish_map(&writer);
}
else {
mpack_finish_array(&writer);
}
}

TEST_ASSERT(mpack_writer_destroy(&writer) == mpack_ok);

mpack_reader_init_data(&reader, buffer, size);
result = unpack_cfl_variant(&reader, &variant);
TEST_CHECK(result != 0);
TEST_CHECK((result == 0) == (expected_result == 0));

if (variant != NULL) {
cfl_variant_destroy(variant);
}

mpack_reader_destroy(&reader);
free(buffer);
}

void test_msgpack_variant_limits()
{
char *buffer;
size_t size;
int result;
mpack_writer_t writer;
mpack_reader_t reader;
struct cfl_variant *variant;
struct cfl_kvlist *kvlist;

check_variant_nesting_limit(CFL_FALSE,
CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH, 0);
check_variant_nesting_limit(CFL_FALSE,
CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH + 1, -1);
check_variant_nesting_limit(CFL_TRUE,
CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH, 0);
check_variant_nesting_limit(CFL_TRUE,
CFL_VARIANT_UTILS_MAXIMUM_NESTING_DEPTH + 1, -1);

mpack_writer_init_growable(&writer, &buffer, &size);
mpack_start_map(&writer, 1);
Expand Down
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