fuzzers/packfile_fuzzer.c

   1 /*
   2  * libgit2 packfile fuzzer target.
   3  *
   4  * Copyright (C) the libgit2 contributors. All rights reserved.
   5  *
   6  * This file is part of libgit2, distributed under the GNU GPL v2 with
   7  * a Linking Exception. For full terms see the included COPYING file.
   8  */
   9
  10 #include <stdio.h>
  11
  12 #include "git2.h"
  13 #include "git2/sys/mempack.h"
  14 #include "common.h"
  15 #include "str.h"
  16
  17 #include "standalone_driver.h"
  18
  19 static git_odb *odb = NULL;
  20 static git_odb_backend *mempack = NULL;
  21
  22 /* Arbitrary object to seed the ODB. */
  23 static const unsigned char base_obj[] = { 07, 076 };
  24 static const unsigned int base_obj_len = 2;
  25
  26 int LLVMFuzzerInitialize(int *argc, char ***argv)
  27 {
  28         GIT_UNUSED(argc);
  29         GIT_UNUSED(argv);
  30
  31         if (git_libgit2_init() < 0) {
  32                 fprintf(stderr, "Failed to initialize libgit2\n");
  33                 abort();
  34         }
  35         if (git_libgit2_opts(GIT_OPT_SET_PACK_MAX_OBJECTS, 10000000) < 0) {
  36                 fprintf(stderr, "Failed to limit maximum pack object count\n");
  37                 abort();
  38         }
  39         if (git_odb_new(&odb) < 0) {
  40                 fprintf(stderr, "Failed to create the odb\n");
  41                 abort();
  42         }
  43         if (git_mempack_new(&mempack) < 0) {
  44                 fprintf(stderr, "Failed to create the mempack\n");
  45                 abort();
  46         }
  47         if (git_odb_add_backend(odb, mempack, 999) < 0) {
  48                 fprintf(stderr, "Failed to add the mempack\n");
  49                 abort();
  50         }
  51         return 0;
  52 }
  53
  54 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
  55 {
  56         git_indexer_progress stats = {0, 0};
  57         git_indexer *indexer = NULL;
  58         git_str path = GIT_STR_INIT;
  59         git_oid oid;
  60         bool append_hash = false;
  61
  62         if (size == 0)
  63                 return 0;
  64
  65         if (!odb || !mempack) {
  66                 fprintf(stderr, "Global state not initialized\n");
  67                 abort();
  68         }
  69         git_mempack_reset(mempack);
  70
  71         if (git_odb_write(&oid, odb, base_obj, base_obj_len, GIT_OBJECT_BLOB) < 0) {
  72                 fprintf(stderr, "Failed to add an object to the odb\n");
  73                 abort();
  74         }
  75
  76         if (git_indexer_new(&indexer, ".", 0, odb, NULL) < 0) {
  77                 fprintf(stderr, "Failed to create the indexer: %s\n",
  78                         git_error_last()->message);
  79                 abort();
  80         }
  81
  82         /*
  83          * If the first byte in the stream has the high bit set, append the
  84          * SHA1 hash so that the packfile is somewhat valid.
  85          */
  86         append_hash = *data & 0x80;
  87         ++data;
  88         --size;
  89
  90         if (git_indexer_append(indexer, data, size, &stats) < 0)
  91                 goto cleanup;
  92         if (append_hash) {
  93                 if (git_odb_hash(&oid, data, size, GIT_OBJECT_BLOB) < 0) {
  94                         fprintf(stderr, "Failed to compute the SHA1 hash\n");
  95                         abort();
  96                 }
  97                 if (git_indexer_append(indexer, &oid.id, GIT_OID_RAWSZ, &stats) < 0) {
  98                         goto cleanup;
  99                 }
 100         }
 101         if (git_indexer_commit(indexer, &stats) < 0)
 102                 goto cleanup;
 103
 104         if (git_str_printf(&path, "pack-%s.idx", git_indexer_name(indexer)) < 0)
 105                 goto cleanup;
 106         p_unlink(git_str_cstr(&path));
 107
 108         git_str_clear(&path);
 109
 110         if (git_str_printf(&path, "pack-%s.pack", git_indexer_name(indexer)) < 0)
 111                 goto cleanup;
 112         p_unlink(git_str_cstr(&path));
 113
 114 cleanup:
 115         git_mempack_reset(mempack);
 116         git_indexer_free(indexer);
 117         git_str_dispose(&path);
 118         return 0;
 119 }