[clang][deps] Fix a use-after-free from expanding response files

clang/lib/Tooling/DependencyScanning/DependencyScannerImpl.cpp

@@ -382,7 +382,8 @@ DignosticsEngineWithDiagOpts::DignosticsEngineWithDiagOpts(
 
 std::pair<std::unique_ptr<driver::Driver>, std::unique_ptr<driver::Compilation>>
 buildCompilation(ArrayRef<std::string> ArgStrs, DiagnosticsEngine &Diags,
-                 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS) {
+                 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
+                 llvm::BumpPtrAllocator &Alloc) {
   SmallVector<const char *, 256> Argv;
   Argv.reserve(ArgStrs.size());
   for (const std::string &Arg : ArgStrs)
@@ -393,7 +394,6 @@ buildCompilation(ArrayRef<std::string> ArgStrs, DiagnosticsEngine &Diags,
       "clang LLVM compiler", FS);
   Driver->setTitle("clang_based_tool");
 
-  llvm::BumpPtrAllocator Alloc;
   bool CLMode = driver::IsClangCL(
       driver::getDriverMode(Argv[0], ArrayRef(Argv).slice(1)));
 

clang/lib/Tooling/DependencyScanning/DependencyScannerImpl.h

@@ -105,7 +105,8 @@ struct TextDiagnosticsPrinterWithOutput {
 
 std::pair<std::unique_ptr<driver::Driver>, std::unique_ptr<driver::Compilation>>
 buildCompilation(ArrayRef<std::string> ArgStrs, DiagnosticsEngine &Diags,
-                 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS);
+                 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
+                 llvm::BumpPtrAllocator &Alloc);
 
 std::unique_ptr<CompilerInvocation>
 createCompilerInvocation(ArrayRef<std::string> CommandLine,

clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp

@@ -78,8 +78,10 @@ static bool forEachDriverJob(
     IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
     llvm::function_ref<bool(const driver::Command &Cmd)> Callback) {
   // Compilation holds a non-owning a reference to the Driver, hence we need to
-  // keep the Driver alive when we use Compilation.
-  auto [Driver, Compilation] = buildCompilation(ArgStrs, Diags, FS);
+  // keep the Driver alive when we use Compilation. Arguments to commands may be
+  // owned by Alloc when expanded from response files.
+  llvm::BumpPtrAllocator Alloc;
+  auto [Driver, Compilation] = buildCompilation(ArgStrs, Diags, FS, Alloc);
   if (!Compilation)
     return false;
   for (const driver::Command &Job : Compilation->getJobs()) {

clang/test/ClangScanDeps/response-file.c

@@ -1,10 +1,12 @@
-// Check that the scanner can handle a response file input.
+// Check that the scanner can handle a response file input. Uses -verbatim-args
+// to ensure response files are expanded by the scanner library and not the
+// argumeent adjuster in clang-scan-deps.
 
 // RUN: rm -rf %t
 // RUN: split-file %s %t
 // RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
 
-// RUN: clang-scan-deps -format experimental-full -compilation-database %t/cdb.json > %t/deps.json
+// RUN: clang-scan-deps -verbatim-args -format experimental-full -compilation-database %t/cdb.json > %t/deps.json
 
 // RUN: cat %t/deps.json | sed 's:\\\\\?:/:g' | FileCheck -DPREFIX=%/t %s
 

clang/tools/clang-scan-deps/ClangScanDeps.cpp

@@ -106,6 +106,7 @@ static constexpr bool DoRoundTripDefault = false;
 #endif
 
 static bool RoundTripArgs = DoRoundTripDefault;
+static bool VerbatimArgs = false;
 
 static void ParseArgs(int argc, char **argv) {
   ScanDepsOptTable Tbl;
@@ -239,6 +240,8 @@ static void ParseArgs(int argc, char **argv) {
 
   RoundTripArgs = Args.hasArg(OPT_round_trip_args);
 
+  VerbatimArgs = Args.hasArg(OPT_verbatim_args);
+
   if (const llvm::opt::Arg *A = Args.getLastArgNoClaim(OPT_DASH_DASH))
     CommandLine.assign(A->getValues().begin(), A->getValues().end());
 }
@@ -883,22 +886,24 @@ int clang_scan_deps_main(int argc, char **argv, const llvm::ToolContext &) {
 
   llvm::cl::PrintOptionValues();
 
-  // Expand response files in advance, so that we can "see" all the arguments
-  // when adjusting below.
-  Compilations = expandResponseFiles(std::move(Compilations),
-                                     llvm::vfs::getRealFileSystem());
+  if (!VerbatimArgs) {
+    // Expand response files in advance, so that we can "see" all the arguments
+    // when adjusting below.
+    Compilations = expandResponseFiles(std::move(Compilations),
+                                       llvm::vfs::getRealFileSystem());
 
-  Compilations = inferTargetAndDriverMode(std::move(Compilations));
+    Compilations = inferTargetAndDriverMode(std::move(Compilations));
 
-  Compilations = inferToolLocation(std::move(Compilations));
+    Compilations = inferToolLocation(std::move(Compilations));
+  }
 
   // The command options are rewritten to run Clang in preprocessor only mode.
   auto AdjustingCompilations =
       std::make_unique<tooling::ArgumentsAdjustingCompilations>(
           std::move(Compilations));
   ResourceDirectoryCache ResourceDirCache;
 
-  AdjustingCompilations->appendArgumentsAdjuster(
+  auto ArgsAdjuster =
       [&ResourceDirCache](const tooling::CommandLineArguments &Args,
                           StringRef FileName) {
         std::string LastO;
@@ -960,7 +965,10 @@ int clang_scan_deps_main(int argc, char **argv, const llvm::ToolContext &) {
         }
         AdjustedArgs.insert(AdjustedArgs.end(), FlagsEnd, Args.end());
         return AdjustedArgs;
-      });
+      };
+
+  if (!VerbatimArgs)
+    AdjustingCompilations->appendArgumentsAdjuster(ArgsAdjuster);
 
   SharedStream Errs(llvm::errs());
 

clang/tools/clang-scan-deps/Opts.td

@@ -44,4 +44,6 @@ def verbose : F<"v", "Use verbose output">;
 
 def round_trip_args : F<"round-trip-args", "verify that command-line arguments are canonical by parsing and re-serializing">;
 
+def verbatim_args : F<"verbatim-args", "Pass commands to the scanner verbatim without adjustments">;
+
 def DASH_DASH : Option<["--"], "", KIND_REMAINING_ARGS>;