thodg/libgit2/fuzzers/packfile_fuzzer.c

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• Hash : 8444b6dc
  Author :
  Date : 2022-01-26T13:07:28
  

  odb_hash*: accept the oid type to hash into The git_odb_hash helper functions should not assume SHA1, and instead should be given the oid type that they're producing.

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• fuzzers/packfile_fuzzer.c

• /*
   * libgit2 packfile fuzzer target.
   *
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #include <stdio.h>
  
  #include "git2.h"
  #include "git2/sys/mempack.h"
  #include "common.h"
  #include "str.h"
  
  #include "standalone_driver.h"
  
  static git_odb *odb = NULL;
  static git_odb_backend *mempack = NULL;
  
  /* Arbitrary object to seed the ODB. */
  static const unsigned char base_obj[] = { 07, 076 };
  static const unsigned int base_obj_len = 2;
  
  int LLVMFuzzerInitialize(int *argc, char ***argv)
  {
  	GIT_UNUSED(argc);
  	GIT_UNUSED(argv);
  
  	if (git_libgit2_init() < 0) {
  		fprintf(stderr, "Failed to initialize libgit2\n");
  		abort();
  	}
  	if (git_libgit2_opts(GIT_OPT_SET_PACK_MAX_OBJECTS, 10000000) < 0) {
  		fprintf(stderr, "Failed to limit maximum pack object count\n");
  		abort();
  	}
  	if (git_odb_new(&odb) < 0) {
  		fprintf(stderr, "Failed to create the odb\n");
  		abort();
  	}
  	if (git_mempack_new(&mempack) < 0) {
  		fprintf(stderr, "Failed to create the mempack\n");
  		abort();
  	}
  	if (git_odb_add_backend(odb, mempack, 999) < 0) {
  		fprintf(stderr, "Failed to add the mempack\n");
  		abort();
  	}
  	return 0;
  }
  
  int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
  {
  	git_indexer_progress stats = {0, 0};
  	git_indexer *indexer = NULL;
  	git_str path = GIT_STR_INIT;
  	git_oid oid;
  	bool append_hash = false;
  
  	if (size == 0)
  		return 0;
  
  	if (!odb || !mempack) {
  		fprintf(stderr, "Global state not initialized\n");
  		abort();
  	}
  	git_mempack_reset(mempack);
  
  	if (git_odb_write(&oid, odb, base_obj, base_obj_len, GIT_OBJECT_BLOB) < 0) {
  		fprintf(stderr, "Failed to add an object to the odb\n");
  		abort();
  	}
  
  	if (git_indexer_new(&indexer, ".", 0, odb, NULL) < 0) {
  		fprintf(stderr, "Failed to create the indexer: %s\n",
  			git_error_last()->message);
  		abort();
  	}
  
  	/*
  	 * If the first byte in the stream has the high bit set, append the
  	 * SHA1 hash so that the packfile is somewhat valid.
  	 */
  	append_hash = *data & 0x80;
  	++data;
  	--size;
  
  	if (git_indexer_append(indexer, data, size, &stats) < 0)
  		goto cleanup;
  	if (append_hash) {
  		if (git_odb_hash(&oid, data, size, GIT_OBJECT_BLOB, GIT_OID_SHA1) < 0) {
  			fprintf(stderr, "Failed to compute the SHA1 hash\n");
  			abort();
  		}
  		if (git_indexer_append(indexer, &oid.id, GIT_OID_SHA1_SIZE, &stats) < 0) {
  			goto cleanup;
  		}
  	}
  	if (git_indexer_commit(indexer, &stats) < 0)
  		goto cleanup;
  
  	if (git_str_printf(&path, "pack-%s.idx", git_indexer_name(indexer)) < 0)
  		goto cleanup;
  	p_unlink(git_str_cstr(&path));
  
  	git_str_clear(&path);
  
  	if (git_str_printf(&path, "pack-%s.pack", git_indexer_name(indexer)) < 0)
  		goto cleanup;
  	p_unlink(git_str_cstr(&path));
  
  cleanup:
  	git_mempack_reset(mempack);
  	git_indexer_free(indexer);
  	git_str_dispose(&path);
  	return 0;
  }
  

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