Commit 52f889ab authored by Matt Morehouse's avatar Matt Morehouse
Browse files

[DFSan] Add __dfsan_load_callback. 

Summary:
When -dfsan-event-callbacks is specified, insert a call to
__dfsan_load_callback() on every load.

Reviewers: vitalybuka, pcc, kcc

Reviewed By: vitalybuka, kcc

Subscribers: hiraditya, #sanitizers, llvm-commits, eugenis, kcc

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D75363
parent 53f51da0

compiler-rt/test/dfsan/event_callbacks.c

+24 −5
Original line number Diff line number Diff line 
// RUN: %clang_dfsan -fno-sanitize=dataflow -fPIE -DCALLBACKS -c %s -o %t-callbacks.o

// RUN: %clang_dfsan -mllvm -dfsan-event-callbacks %s %t-callbacks.o -o %t

// RUN: %clang_dfsan -fno-sanitize=dataflow -O2 -fPIE -DCALLBACKS -c %s -o %t-callbacks.o

// RUN: %clang_dfsan -O2 -mllvm -dfsan-event-callbacks %s %t-callbacks.o -o %t

// RUN: %run %t 2>&1 | FileCheck %s



// Tests that callbacks are inserted for store events when
@@ -35,12 +35,16 @@ void __dfsan_store_callback(dfsan_label Label) { 
    assert(0);

  }



  // CHECK: Label 1 stored to memory

  // CHECK: Label 2 stored to memory

  // CHECK: Label 3 stored to memory

  fprintf(stderr, "Label %u stored to memory\n", Label);

}



void __dfsan_load_callback(dfsan_label Label) {

  if (!Label)

    return;



  fprintf(stderr, "Label %u loaded from memory\n", Label);

}



#else

// Compile this code with DFSan and -dfsan-event-callbacks to insert the

// callbacks.
@@ -57,10 +61,25 @@ int main(void) { 
  dfsan_set_label(LabelJ, &J, sizeof(J));

  LabelIJ = dfsan_union(LabelI, LabelJ);



  // CHECK: Label 1 stored to memory

  volatile int Sink = I;



  // CHECK: Label 1 loaded from memory

  assert(Sink == 1);



  // CHECK: Label 2 stored to memory

  Sink = J;



  // CHECK: Label 2 loaded from memory

  assert(Sink == 2);



  // CHECK: Label 2 loaded from memory

  // CHECK: Label 3 stored to memory

  Sink += I;



  // CHECK: Label 3 loaded from memory

  assert(Sink == 3);



  return 0;

}

llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp

+13 −4
Original line number Diff line number Diff line
@@ -163,10 +163,11 @@ static cl::opt<bool> ClDebugNonzeroLabels( 
    cl::Hidden);



// Experimental feature that inserts callbacks for certain data events.

// Currently callbacks are only inserted for stores.

// Currently callbacks are only inserted for loads and stores.

//

// If this flag is set to true, the user must provide definitions for the

// following callback functions:

//   void __dfsan_load_callback(dfsan_label Label);

//   void __dfsan_store_callback(dfsan_label Label);

static cl::opt<bool> ClEventCallbacks(

    "dfsan-event-callbacks",
@@ -356,7 +357,7 @@ class DataFlowSanitizer : public ModulePass { 
  FunctionType *DFSanSetLabelFnTy;

  FunctionType *DFSanNonzeroLabelFnTy;

  FunctionType *DFSanVarargWrapperFnTy;

  FunctionType *DFSanStoreCallbackFnTy;

  FunctionType *DFSanLoadStoreCallbackFnTy;

  FunctionCallee DFSanUnionFn;

  FunctionCallee DFSanCheckedUnionFn;

  FunctionCallee DFSanUnionLoadFn;
@@ -364,6 +365,7 @@ class DataFlowSanitizer : public ModulePass { 
  FunctionCallee DFSanSetLabelFn;

  FunctionCallee DFSanNonzeroLabelFn;

  FunctionCallee DFSanVarargWrapperFn;

  FunctionCallee DFSanLoadCallbackFn;

  FunctionCallee DFSanStoreCallbackFn;

  MDNode *ColdCallWeights;

  DFSanABIList ABIList;
@@ -596,7 +598,7 @@ bool DataFlowSanitizer::doInitialization(Module &M) { 
      Type::getVoidTy(*Ctx), None, /*isVarArg=*/false);

  DFSanVarargWrapperFnTy = FunctionType::get(

      Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);

  DFSanStoreCallbackFnTy =

  DFSanLoadStoreCallbackFnTy =

      FunctionType::get(Type::getVoidTy(*Ctx), ShadowTy, /*isVarArg=*/false);



  if (GetArgTLSPtr) {
@@ -798,8 +800,10 @@ bool DataFlowSanitizer::runOnModule(Module &M) { 
  DFSanVarargWrapperFn = Mod->getOrInsertFunction("__dfsan_vararg_wrapper",

                                                  DFSanVarargWrapperFnTy);



  DFSanLoadCallbackFn = Mod->getOrInsertFunction("__dfsan_load_callback",

                                                 DFSanLoadStoreCallbackFnTy);

  DFSanStoreCallbackFn = Mod->getOrInsertFunction("__dfsan_store_callback",

                                                  DFSanStoreCallbackFnTy);

                                                  DFSanLoadStoreCallbackFnTy);



  std::vector<Function *> FnsToInstrument;

  SmallPtrSet<Function *, 2> FnsWithNativeABI;
@@ -812,6 +816,7 @@ bool DataFlowSanitizer::runOnModule(Module &M) { 
        &i != DFSanSetLabelFn.getCallee()->stripPointerCasts() &&

        &i != DFSanNonzeroLabelFn.getCallee()->stripPointerCasts() &&

        &i != DFSanVarargWrapperFn.getCallee()->stripPointerCasts() &&

        &i != DFSanLoadCallbackFn.getCallee()->stripPointerCasts() &&

        &i != DFSanStoreCallbackFn.getCallee()->stripPointerCasts())

      FnsToInstrument.push_back(&i);

  }
@@ -1344,6 +1349,10 @@ void DFSanVisitor::visitLoadInst(LoadInst &LI) { 
    DFSF.NonZeroChecks.push_back(Shadow);



  DFSF.setShadow(&LI, Shadow);

  if (ClEventCallbacks) {

    IRBuilder<> IRB(&LI);

    IRB.CreateCall(DFSF.DFS.DFSanLoadCallbackFn, Shadow);

  }

}



void DFSanFunction::storeShadow(Value *Addr, uint64_t Size, Align Alignment,