OSS-Fuzz: Add new fuzzer targets Fortran Parser

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>

Tests/Fuzzing/CMakeLists.txt

@@ -100,3 +100,6 @@ add_fuzzer(cmFileLockFuzzer cmFileLockFuzzer.cxx)
 
 # CMake script fuzzer
 add_fuzzer(cmScriptFuzzer cmScriptFuzzer.cxx)
+
+# Fortran dependency scanner fuzzer
+add_fuzzer(cmFortranParserFuzzer cmFortranParserFuzzer.cxx)

Tests/Fuzzing/cmFortranParser.dict

@@ -0,0 +1,36 @@
+# Fortran dependency scanner dictionary
+
+# Module dependency statements
+"module "
+"submodule "
+"end module"
+"use "
+"use, intrinsic ::"
+"only:"
+"include "
+"#include "
+
+# Submodule parent syntax
+"submodule ("
+")"
+":"
+
+# Preprocessor directives the scanner tracks
+"#define"
+"#undef"
+"#ifdef"
+"#ifndef"
+"#if defined"
+"#elif"
+"#else"
+"#endif"
+
+# Fixed-form and continuation punctuation
+"&"
+"!"
+"c "
+"*"
+"'"
+"\""
+";"
+"::"

Tests/Fuzzing/cmFortranParserFuzzer.cxx

@@ -0,0 +1,79 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file LICENSE.rst or https://cmake.org/licensing for details.  */
+
+/*
+ * Fuzzer for CMake's Fortran dependency scanner
+ *
+ * CMake runs a flex lexer and a bison parser over Fortran sources to discover
+ * module dependencies: MODULE, SUBMODULE, USE and INCLUDE statements, plus the
+ * preprocessor directives that guard them. This fuzzer drives that scanner.
+ */
+
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <set>
+#include <string>
+#include <vector>
+
+#include <unistd.h>
+
+#include "cmFortranParser.h"
+#include "cmSystemTools.h"
+
+static constexpr size_t kMaxInputSize = 256 * 1024;
+static std::string g_testDir;
+
+extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv)
+{
+  (void)argc;
+  (void)argv;
+
+  char tmpl[] = "/tmp/cmake_fuzz_fortran_XXXXXX";
+  char* dir = mkdtemp(tmpl);
+  if (dir) {
+    g_testDir = dir;
+  } else {
+    g_testDir = "/tmp/cmake_fuzz_fortran";
+    cmSystemTools::MakeDirectory(g_testDir);
+  }
+
+  return 0;
+}
+
+extern "C" int LLVMFuzzerTestOneInput(uint8_t const* data, size_t size)
+{
+  if (size == 0 || size > kMaxInputSize) {
+    return 0;
+  }
+
+  std::string const source = g_testDir + "/test.f90";
+  {
+    FILE* fp = fopen(source.c_str(), "wb");
+    if (!fp) {
+      return 0;
+    }
+    fwrite(data, 1, size, fp);
+    fclose(fp);
+  }
+
+  cmFortranCompiler compiler;
+  compiler.Id = "GNU";
+  compiler.SModSep = "@";
+  compiler.SModExt = ".smod";
+
+  cmFortranSourceInfo info;
+  info.Source = source;
+
+  std::vector<std::string> const includes;
+  std::set<std::string> const defines;
+
+  cmFortranParser parser(compiler, includes, defines, info);
+  if (cmFortranParser_FilePush(&parser, source.c_str())) {
+    cmFortran_yyparse(parser.Scanner);
+  }
+
+  unlink(source.c_str());
+
+  return 0;
+}

Tests/Fuzzing/corpus/fortran/continuation.f90

@@ -0,0 +1,4 @@
+module a
+  use b
+  &
+  use c

Tests/Fuzzing/corpus/fortran/fixedform.f

@@ -0,0 +1,3 @@
+      MODULE FIXED
+      USE OTHER
+      END

Tests/Fuzzing/corpus/fortran/module.f90

@@ -0,0 +1,4 @@
+module geometry
+  implicit none
+  integer, parameter :: dp = kind(1.0d0)
+end module geometry

Tests/Fuzzing/corpus/fortran/preproc.F90

@@ -0,0 +1,7 @@
+#define HAVE_MPI 1
+#ifdef HAVE_MPI
+      use mpi
+#else
+      use serial_stub
+#endif
+      include 'missing.inc'

Tests/Fuzzing/corpus/fortran/submodule.f90

@@ -0,0 +1,6 @@
+submodule (parent:child) impl
+  implicit none
+contains
+  subroutine s()
+  end subroutine s
+end submodule impl

Tests/Fuzzing/corpus/fortran/use.f90

@@ -0,0 +1,5 @@
+program main
+  use geometry, only: dp
+  use, intrinsic :: iso_fortran_env
+  implicit none
+end program main