Add experimental clang/driver flag -fsanitize-address-field-padding=N

Summary:
This change adds an experimental flag -fsanitize-address-field-padding=N (0, 1, 2)
to clang and driver. With this flag ASAN will be able to detect some cases of
intra-object-overflow bugs,
see https://code.google.com/p/address-sanitizer/wiki/IntraObjectOverflow

There is no actual functionality here yet, just the flag parsing.
The functionality is being reviewed at http://reviews.llvm.org/D5687

Test Plan: Build and run SPEC, LLVM Bootstrap, Chrome with this flag.

Reviewers: samsonov

Reviewed By: samsonov

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D5676

llvm-svn: 219417

6 files changed, 34 insertions, 1 deletions

diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
index 1dac4b42775..47a74f06142 100644
--- a/clang/include/clang/Basic/LangOptions.h
+++ b/clang/include/clang/Basic/LangOptions.h
@@ -26,6 +26,9 @@ namespace clang {
 struct SanitizerOptions {
 #define SANITIZER(NAME, ID) unsigned ID : 1;
 #include "clang/Basic/Sanitizers.def"
+  /// \brief Controls how agressive is asan field padding (0: none, 1: least
+  /// aggressive, 2: more aggressive).
+  unsigned SanitizeAddressFieldPadding : 2;
 
   /// \brief Cached set of sanitizer options with all sanitizers disabled.
   static const SanitizerOptions Disabled;
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 1d2ef6f988c..b24d16ba068 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -526,6 +526,9 @@ def fsanitize_memory_track_origins : Flag<["-"], "fsanitize-memory-track-origins
 def fno_sanitize_memory_track_origins : Flag<["-"], "fno-sanitize-memory-track-origins">,
                                         Group<f_clang_Group>, Flags<[CC1Option]>,
                                         HelpText<"Disable origins tracking in MemorySanitizer">;
+def fsanitize_address_field_padding : Joined<["-"], "fsanitize-address-field-padding=">,
+                                        Group<f_clang_Group>, Flags<[CC1Option]>,
+                                        HelpText<"Level of field padding for AddressSanitizer">;
 def fsanitize_recover : Flag<["-"], "fsanitize-recover">,
                         Group<f_clang_Group>;
 def fno_sanitize_recover : Flag<["-"], "fno-sanitize-recover">,
diff --git a/clang/include/clang/Driver/SanitizerArgs.h b/clang/include/clang/Driver/SanitizerArgs.h
index 8f011abba81..46fd4b6d5ea 100644
--- a/clang/include/clang/Driver/SanitizerArgs.h
+++ b/clang/include/clang/Driver/SanitizerArgs.h
@@ -49,6 +49,7 @@ class SanitizerArgs {
 
   std::string BlacklistFile;
   int MsanTrackOrigins;
+  int AsanFieldPadding;
   bool AsanZeroBaseShadow;
   bool UbsanTrapOnError;
   bool AsanSharedRuntime;
diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
index c192034236d..98e5480136b 100644
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -25,6 +25,7 @@ void SanitizerArgs::clear() {
   Kind = 0;
   BlacklistFile = "";
   MsanTrackOrigins = 0;
+  AsanFieldPadding = 0;
   AsanZeroBaseShadow = false;
   UbsanTrapOnError = false;
   AsanSharedRuntime = false;
@@ -164,6 +165,15 @@ SanitizerArgs::SanitizerArgs(const ToolChain &TC,
         (TC.getTriple().getEnvironment() == llvm::Triple::Android);
     AsanZeroBaseShadow =
         (TC.getTriple().getEnvironment() == llvm::Triple::Android);
+    if (Arg *A =
+            Args.getLastArg(options::OPT_fsanitize_address_field_padding)) {
+        StringRef S = A->getValue();
+        // Legal values are 0 and 1, 2, but in future we may add more levels.
+        if (S.getAsInteger(0, AsanFieldPadding) || AsanFieldPadding < 0 ||
+            AsanFieldPadding > 2) {
+          D.Diag(diag::err_drv_invalid_value) << A->getAsString(Args) << S;
+        }
+    }
   }
 
   // Parse -link-cxx-sanitizer flag.
@@ -191,7 +201,9 @@ void SanitizerArgs::addArgs(const llvm::opt::ArgList &Args,
   if (MsanTrackOrigins)
     CmdArgs.push_back(Args.MakeArgString("-fsanitize-memory-track-origins=" +
                                          llvm::utostr(MsanTrackOrigins)));
-
+  if (AsanFieldPadding)
+    CmdArgs.push_back(Args.MakeArgString("-fsanitize-address-field-padding=" +
+                                         llvm::utostr(AsanFieldPadding)));
   // Workaround for PR16386.
   if (needsMsanRt())
     CmdArgs.push_back(Args.MakeArgString("-fno-assume-sane-operator-new"));
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 043141ad673..25d444eeb81 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1628,6 +1628,9 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
       break;
     }
   }
+  // -fsanitize-address-field-padding=N has to be a LangOpt, parse it here.
+  Opts.Sanitize.SanitizeAddressFieldPadding =
+      getLastArgIntValue(Args, OPT_fsanitize_address_field_padding, 0, Diags);
 }
 
 static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
diff --git a/clang/test/Driver/fsanitize.c b/clang/test/Driver/fsanitize.c
index 5099c04ce09..8eb5de462bb 100644
--- a/clang/test/Driver/fsanitize.c
+++ b/clang/test/Driver/fsanitize.c
@@ -80,6 +80,17 @@
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins=3 -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-3
 // CHECK-TRACK-ORIGINS-3: error: invalid value '3' in '-fsanitize-memory-track-origins=3'
 
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=address -fsanitize-address-field-padding=0 %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-FIELD-PADDING-0
+// CHECK-ASAN-FIELD-PADDING-0-NOT: -fsanitize-address-field-padding
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=address -fsanitize-address-field-padding=1 %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-FIELD-PADDING-1
+// CHECK-ASAN-FIELD-PADDING-1: -fsanitize-address-field-padding=1
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=address -fsanitize-address-field-padding=2 %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-FIELD-PADDING-2
+// CHECK-ASAN-FIELD-PADDING-2: -fsanitize-address-field-padding=2
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=address -fsanitize-address-field-padding=3 %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-FIELD-PADDING-3
+// CHECK-ASAN-FIELD-PADDING-3: error: invalid value '3' in '-fsanitize-address-field-padding=3'
+// RUN: %clang -target x86_64-linux-gnu -fsanitize-address-field-padding=2 %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-FIELD-PADDING-NO-ASAN
+// CHECK-ASAN-FIELD-PADDING-NO-ASAN: warning: argument unused during compilation: '-fsanitize-address-field-padding=2'
+
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=vptr -fno-sanitize=vptr -fsanitize=undefined,address %s -### 2>&1
 // OK