[repacker] begin implementing a fuzzer for the repacker api.

This commit is contained in:
Garret Rieger 2022-09-07 22:21:16 +00:00
parent 2658370f00
commit 985b19f678
4 changed files with 155 additions and 0 deletions

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@ -941,6 +941,18 @@ struct graph_t
return made_change;
}
bool is_fully_connected ()
{
update_parents();
for (unsigned i = 0; i < root_idx (); i++)
{
if (!vertices_[i].parents)
return false;
}
return true;
}
void print_orphaned_nodes ()
{
if (!DEBUG_ENABLED(SUBSET_REPACK)) return;

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@ -376,6 +376,12 @@ hb_resolve_overflows (const T& packed,
unsigned max_rounds = 20,
bool recalculate_extensions = false) {
graph_t sorted_graph (packed);
if (!sorted_graph.is_fully_connected ())
{
DEBUG_MSG (SUBSET_REPACK, nullptr, "Input graph is not fully connected.");
return nullptr;
}
if (!hb_resolve_graph_overflows (table_tag, max_rounds, recalculate_extensions, sorted_graph))
return nullptr;

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@ -0,0 +1,134 @@
#include "hb-fuzzer.hh"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "hb-subset-repacker.h"
typedef struct
{
uint16_t parent;
uint16_t delta;
uint16_t position;
uint8_t width;
} link_t;
template <typename T>
bool read(const uint8_t** data, size_t* size, T* out)
{
if (*size < sizeof (T)) return false;
*out = * ((T*) *data);
*data += sizeof (T);
*size -= sizeof (T);
return true;
}
void cleanup (hb_object_t* objects, uint16_t num_objects)
{
for (uint32_t i = 0; i < num_objects; i++)
free (objects[i].real_links);
}
void add_links_to_objects (hb_object_t* objects, uint16_t num_objects,
link_t* links, uint16_t num_links)
{
unsigned* link_count = (unsigned*) calloc (num_objects, sizeof (unsigned));
for (uint32_t i = 0; i < num_links; i++)
{
uint16_t parent_idx = links[i].parent;
link_count[parent_idx]++;
}
for (uint32_t i = 0; i < num_objects; i++)
{
objects[i].num_real_links = link_count[i];
objects[i].real_links = (hb_link_t*) calloc (link_count[i], sizeof (hb_link_t));
objects[i].num_virtual_links = 0;
objects[i].virtual_links = nullptr;
}
for (uint32_t i = 0; i < num_links; i++)
{
uint16_t parent_idx = links[i].parent;
uint16_t child_idx = links[i].parent + links[i].delta + 1;
hb_link_t* link = &(objects[parent_idx].real_links[link_count[parent_idx] - 1]);
link->width = links[i].width;
link->position = links[i].position;
link->objidx = child_idx;
link_count[parent_idx]--;
}
bool* reachable = (bool*) calloc (num_objects, sizeof (bool));
free (reachable);
free (link_count);
}
extern "C" int LLVMFuzzerTestOneInput (const uint8_t *data, size_t size)
{
alloc_state = _fuzzing_alloc_state (data, size);
uint16_t num_objects = 0;
hb_object_t* objects = nullptr;
uint16_t num_real_links = 0;
link_t* links = nullptr;
hb_tag_t table_tag;
if (!read<hb_tag_t> (&data, &size, &table_tag)) goto end;
if (!read<uint16_t> (&data, &size, &num_objects)) goto end;
objects = (hb_object_t*) calloc (num_objects, sizeof (hb_object_t));
for (uint32_t i = 0; i < num_objects; i++)
{
uint16_t blob_size;
if (!read<uint16_t> (&data, &size, &blob_size)) goto end;
if (size < blob_size) goto end;
objects[i].head = (char*) data;
objects[i].tail = (char*) (data + blob_size);
size -= blob_size;
data += blob_size;
}
if (!read<uint16_t> (&data, &size, &num_real_links)) goto end;
links = (link_t*) calloc (num_real_links, sizeof (link_t));
for (uint32_t i = 0; i < num_real_links; i++)
{
if (!read<link_t> (&data, &size, &links[i])) goto end;
uint32_t child_idx = ((uint32_t) links[i].parent) + ((uint32_t) links[i].delta) + 1;
if (links[i].parent >= num_objects
|| child_idx >= num_objects)
goto end;
if (links[i].width < 2 || links[i].width > 4) goto end;
}
add_links_to_objects (objects, num_objects,
links, num_real_links);
hb_blob_destroy (hb_subset_repack_or_fail (table_tag,
objects,
num_objects));
end:
if (objects)
{
cleanup (objects, num_objects);
free (objects);
}
free (links);
return 0;
}

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@ -1,6 +1,7 @@
tests = [
'hb-shape-fuzzer.cc',
'hb-subset-fuzzer.cc',
'hb-repacker-fuzzer.cc',
'hb-set-fuzzer.cc',
'hb-draw-fuzzer.cc',
]
@ -19,6 +20,8 @@ foreach file_name : tests
extra_cpp_args += '-DHB_IS_IN_FUZZER'
endif
# TODO tie this to the experimental api setting.
extra_cpp_args += '-DHB_EXPERIMENTAL_API'
exe = executable(test_name, sources,
cpp_args: cpp_args + extra_cpp_args,
include_directories: [incconfig, incsrc],