thodg/libgit2/fuzzers/commit_graph_fuzzer.c

• Show log

  Commit

• Hash : 25b75cd9
  Author :
  Date : 2021-03-10T07:06:15
  

  commit-graph: Create `git_commit_graph` as an abstraction for the file This change does a medium-size refactor of the git_commit_graph_file and the interaction with the ODB. Now instead of the ODB owning a direct reference to the git_commit_graph_file, there will be an intermediate git_commit_graph. The main advantage of that is that now end users can explicitly set a git_commit_graph that is eagerly checked for errors, while still being able to lazily use the commit-graph in a regular ODB, if the file is present.

Download

• fuzzers/commit_graph_fuzzer.c

• /*
   * libgit2 commit-graph 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 "buffer.h"
  #include "common.h"
  #include "futils.h"
  #include "hash.h"
  #include "commit_graph.h"
  
  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();
  	}
  	return 0;
  }
  
  int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
  {
  	git_commit_graph_file file = {{0}};
  	git_commit_graph_entry e;
  	git_buf commit_graph_buf = GIT_BUF_INIT;
  	git_oid oid = {{0}};
  	bool append_hash = false;
  
  	if (size < 4)
  		return 0;
  
  	/*
  	 * If the first byte in the stream has the high bit set, append the
  	 * SHA1 hash so that the file is somewhat valid.
  	 */
  	append_hash = *data & 0x80;
  	/* Keep a 4-byte alignment to avoid unaligned accesses. */
  	data += 4;
  	size -= 4;
  
  	if (append_hash) {
  		if (git_buf_init(&commit_graph_buf, size + sizeof(oid)) < 0)
  			goto cleanup;
  		if (git_hash_buf(&oid, data, size) < 0) {
  			fprintf(stderr, "Failed to compute the SHA1 hash\n");
  			abort();
  		}
  		memcpy(commit_graph_buf.ptr, data, size);
  		memcpy(commit_graph_buf.ptr + size, &oid, sizeof(oid));
  	} else {
  		git_buf_attach_notowned(&commit_graph_buf, (char *)data, size);
  	}
  
  	if (git_commit_graph_file_parse(
  			    &file,
  			    (const unsigned char *)git_buf_cstr(&commit_graph_buf),
  			    git_buf_len(&commit_graph_buf))
  	    < 0)
  		goto cleanup;
  
  	/* Search for any oid, just to exercise that codepath. */
  	if (git_commit_graph_entry_find(&e, &file, &oid, GIT_OID_HEXSZ) < 0)
  		goto cleanup;
  
  cleanup:
  	git_commit_graph_file_close(&file);
  	git_buf_dispose(&commit_graph_buf);
  	return 0;
  }
  

Download