fuzzers/commit_graph_fuzzer.c

   1 /*
   2  * libgit2 commit-graph 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
  14 #include "buffer.h"
  15 #include "common.h"
  16 #include "futils.h"
  17 #include "hash.h"
  18 #include "commit_graph.h"
  19
  20 int LLVMFuzzerInitialize(int *argc, char ***argv)
  21 {
  22         GIT_UNUSED(argc);
  23         GIT_UNUSED(argv);
  24
  25         if (git_libgit2_init() < 0) {
  26                 fprintf(stderr, "Failed to initialize libgit2\n");
  27                 abort();
  28         }
  29         return 0;
  30 }
  31
  32 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
  33 {
  34         git_commit_graph_file file = {{0}};
  35         git_commit_graph_entry e;
  36         git_buf commit_graph_buf = GIT_BUF_INIT;
  37         git_oid oid = {{0}};
  38         bool append_hash = false;
  39
  40         if (size < 4)
  41                 return 0;
  42
  43         /*
  44          * If the first byte in the stream has the high bit set, append the
  45          * SHA1 hash so that the file is somewhat valid.
  46          */
  47         append_hash = *data & 0x80;
  48         /* Keep a 4-byte alignment to avoid unaligned accesses. */
  49         data += 4;
  50         size -= 4;
  51
  52         if (append_hash) {
  53                 if (git_buf_init(&commit_graph_buf, size + sizeof(oid)) < 0)
  54                         goto cleanup;
  55                 if (git_hash_buf(&oid, data, size) < 0) {
  56                         fprintf(stderr, "Failed to compute the SHA1 hash\n");
  57                         abort();
  58                 }
  59                 memcpy(commit_graph_buf.ptr, data, size);
  60                 memcpy(commit_graph_buf.ptr + size, &oid, sizeof(oid));
  61         } else {
  62                 git_buf_attach_notowned(&commit_graph_buf, (char *)data, size);
  63         }
  64
  65         if (git_commit_graph_file_parse(
  66                             &file,
  67                             (const unsigned char *)git_buf_cstr(&commit_graph_buf),
  68                             git_buf_len(&commit_graph_buf))
  69             < 0)
  70                 goto cleanup;
  71
  72         /* Search for any oid, just to exercise that codepath. */
  73         if (git_commit_graph_entry_find(&e, &file, &oid, GIT_OID_HEXSZ) < 0)
  74                 goto cleanup;
  75
  76 cleanup:
  77         git_commit_graph_file_close(&file);
  78         git_buf_dispose(&commit_graph_buf);
  79         return 0;
  80 }