[libFuzzer] Error and exit if user supplied fuzzer writeable directories don't exist
Currently, libFuzzer will exit with an error message if a non-existent
corpus directory is provided. However, if a user provides a non-existent
directory for the `artifact_prefix`, `exact_artifact_path`, or
`features_dir`, libFuzzer will continue execution but silently fail to
write artifacts/features.
To improve the user experience, this PR adds validation for the existence of
all user supplied directories before executing the main fuzzing loop. If they
don't exist, libFuzzer will exit with an error message.
Patch By: dgg5503
Reviewed By: morehouse
Differential Revision: https://reviews.llvm.org/D84808
GitOrigin-RevId: 2392ff093af128d5e46ce31e2ffa0b3e17185e32
diff --git a/FuzzerDriver.cpp b/FuzzerDriver.cpp
index bed9e84..4669b12 100644
--- a/FuzzerDriver.cpp
+++ b/FuzzerDriver.cpp
@@ -250,6 +250,13 @@
}
}
+static void ValidateDirectoryExists(const std::string &Path) {
+ if (!Path.empty() && !IsDirectory(Path)) {
+ Printf("ERROR: The required directory \"%s\" does not exist\n", Path.c_str());
+ exit(1);
+ }
+}
+
std::string CloneArgsWithoutX(const Vector<std::string> &Args,
const char *X1, const char *X2) {
std::string Cmd;
@@ -678,13 +685,32 @@
Options.MallocLimitMb = Options.RssLimitMb;
if (Flags.runs >= 0)
Options.MaxNumberOfRuns = Flags.runs;
- if (!Inputs->empty() && !Flags.minimize_crash_internal_step)
- Options.OutputCorpus = (*Inputs)[0];
+ if (!Inputs->empty() && !Flags.minimize_crash_internal_step) {
+ // Ensure output corpus assumed to be the first arbitrary argument input
+ // is not a path to an existing file.
+ std::string OutputCorpusDir = (*Inputs)[0];
+ if (!IsFile(OutputCorpusDir)) {
+ Options.OutputCorpus = OutputCorpusDir;
+ ValidateDirectoryExists(Options.OutputCorpus);
+ }
+ }
Options.ReportSlowUnits = Flags.report_slow_units;
- if (Flags.artifact_prefix)
+ if (Flags.artifact_prefix) {
Options.ArtifactPrefix = Flags.artifact_prefix;
- if (Flags.exact_artifact_path)
+
+ // Since the prefix could be a full path to a file name prefix, assume
+ // that if the path ends with the platform's separator that a directory
+ // is desired
+ std::string ArtifactPathDir = Options.ArtifactPrefix;
+ if (!IsSeparator(ArtifactPathDir[ArtifactPathDir.length() - 1])) {
+ ArtifactPathDir = DirName(ArtifactPathDir);
+ }
+ ValidateDirectoryExists(ArtifactPathDir);
+ }
+ if (Flags.exact_artifact_path) {
Options.ExactArtifactPath = Flags.exact_artifact_path;
+ ValidateDirectoryExists(DirName(Options.ExactArtifactPath));
+ }
Vector<Unit> Dictionary;
if (Flags.dict)
if (!ParseDictionaryFile(FileToString(Flags.dict), &Dictionary))
@@ -707,8 +733,10 @@
Options.FocusFunction = Flags.focus_function;
if (Flags.data_flow_trace)
Options.DataFlowTrace = Flags.data_flow_trace;
- if (Flags.features_dir)
+ if (Flags.features_dir) {
Options.FeaturesDir = Flags.features_dir;
+ ValidateDirectoryExists(Options.FeaturesDir);
+ }
if (Flags.collect_data_flow)
Options.CollectDataFlow = Flags.collect_data_flow;
if (Flags.stop_file)
diff --git a/FuzzerIO.h b/FuzzerIO.h
index 6e4368b..8def2e9 100644
--- a/FuzzerIO.h
+++ b/FuzzerIO.h
@@ -58,6 +58,7 @@
// Platform specific functions:
bool IsFile(const std::string &Path);
+bool IsDirectory(const std::string &Path);
size_t FileSize(const std::string &Path);
void ListFilesInDirRecursive(const std::string &Dir, long *Epoch,
@@ -82,6 +83,7 @@
void GetSizedFilesFromDir(const std::string &Dir, Vector<SizedFile> *V);
char GetSeparator();
+bool IsSeparator(char C);
// Similar to the basename utility: returns the file name w/o the dir prefix.
std::string Basename(const std::string &Path);
diff --git a/FuzzerIOPosix.cpp b/FuzzerIOPosix.cpp
index aac85b0..0da063a 100644
--- a/FuzzerIOPosix.cpp
+++ b/FuzzerIOPosix.cpp
@@ -31,7 +31,7 @@
return S_ISREG(St.st_mode);
}
-static bool IsDirectory(const std::string &Path) {
+bool IsDirectory(const std::string &Path) {
struct stat St;
if (stat(Path.c_str(), &St))
return false;
@@ -104,6 +104,10 @@
return '/';
}
+bool IsSeparator(char C) {
+ return C == '/';
+}
+
FILE* OpenFile(int Fd, const char* Mode) {
return fdopen(Fd, Mode);
}
diff --git a/FuzzerIOWindows.cpp b/FuzzerIOWindows.cpp
index 651283a..61ad35e 100644
--- a/FuzzerIOWindows.cpp
+++ b/FuzzerIOWindows.cpp
@@ -76,6 +76,18 @@
return FileAttrs & FILE_ATTRIBUTE_DIRECTORY;
}
+bool IsDirectory(const std::string &Path) {
+ DWORD Att = GetFileAttributesA(Path.c_str());
+
+ if (Att == INVALID_FILE_ATTRIBUTES) {
+ Printf("GetFileAttributesA() failed for \"%s\" (Error code: %lu).\n",
+ Path.c_str(), GetLastError());
+ return false;
+ }
+
+ return IsDir(Att);
+}
+
std::string Basename(const std::string &Path) {
size_t Pos = Path.find_last_of("/\\");
if (Pos == std::string::npos) return Path;
@@ -227,7 +239,7 @@
return _get_osfhandle(fd);
}
-static bool IsSeparator(char C) {
+bool IsSeparator(char C) {
return C == '\\' || C == '/';
}
