[AddressSanitizer] Instrument byval call arguments

[thejh]

Summary

In the LLVM IR, "call" instructions read memory for each byval operand.
For example:

$ cat blah.c
struct foo { void *a, *b, *c; };
struct bar { struct foo foo; };
void func1(const struct foo);
void func2(struct bar *bar) { func1(bar->foo); }
$ [...]/bin/clang -S -flto -c blah.c -O2 ; cat blah.s
[...]
define dso_local void @func2(%struct.bar* %bar) local_unnamed_addr #0 {
entry:

%foo = getelementptr inbounds %struct.bar, %struct.bar* %bar, i64 0, i32 0
tail call void @func1(%struct.foo* byval(%struct.foo) align 8 %foo) #2
ret void

}
[...]
$ [...]/bin/clang -S -c blah.c -O2 ; cat blah.s
[...]
func2: # @func2
[...]
subq $24, %rsp
[...]
movq 16(%rdi), %rax
movq %rax, 16(%rsp)
movups (%rdi), %xmm0
movups %xmm0, (%rsp)
callq func1
addq $24, %rsp
[...]
retq

Let ASAN instrument these hidden memory accesses.

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

 //===- AddressSanitizer.cpp - memory error detector -----------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
if (F && (F->getName().startswith("llvm.masked.load.") ||
       auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
       unsigned Alignment = 1;
       // Otherwise no alignment guarantees. We probably got Undef.
       if (auto AlignmentConstant =
               dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
         Alignment = (unsigned)AlignmentConstant->getZExtValue();
       Value *Mask = CI->getOperand(2 + OpOffset);
       Interesting.emplace_back(I, OpOffset, IsWrite, Ty, Alignment, Mask);
+    } else {
+      for (unsigned ArgNo = 0; ArgNo < CI->getNumArgOperands(); ArgNo++) {
+        if (!CI->isByValArgument(ArgNo) ||
+            ignoreAccess(CI->getArgOperand(ArgNo)))
+          continue;
+        Type *Ty = CI->getParamByValType(ArgNo);
+        Interesting.emplace_back(I, ArgNo, false, Ty, 1);
+      }
     }
   }
 }
 
 static bool isPointerOperand(Value *V) {
   return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
 }
 

llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

 //===- HWAddressSanitizer.cpp - detector of uninitialized reads -------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
if (!ClInstrumentAtomics || ignoreAccess(RMW->getPointerOperand()))
       return;
     Interesting.emplace_back(I, RMW->getPointerOperandIndex(), true,
                              RMW->getValOperand()->getType(), 0);
   } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
     if (!ClInstrumentAtomics || ignoreAccess(XCHG->getPointerOperand()))
       return;
     Interesting.emplace_back(I, XCHG->getPointerOperandIndex(), true,
                              XCHG->getCompareOperand()->getType(), 0);
+  } else if (auto CI = dyn_cast<CallInst>(I)) {
+    for (unsigned ArgNo = 0; ArgNo < CI->getNumArgOperands(); ArgNo++) {
+      if (!CI->isByValArgument(ArgNo) || ignoreAccess(CI->getArgOperand(ArgNo)))
+        continue;
+      Type *Ty = CI->getParamByValType(ArgNo);
+      Interesting.emplace_back(I, ArgNo, false, Ty, 1);
+    }
   }
 }
 
 static unsigned getPointerOperandIndex(Instruction *I) {
   if (LoadInst *LI = dyn_cast<LoadInst>(I))
     return LI->getPointerOperandIndex();
   if (StoreInst *SI = dyn_cast<StoreInst>(I))
     return SI->getPointerOperandIndex();

llvm/test/Instrumentation/AddressSanitizer/byval-args.ll

+; RUN: opt < %s -asan -S | FileCheck %s
+; Test that for call instructions, the by-value arguments are instrumented.
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.bar = type { %struct.foo }
+%struct.foo = type { i8*, i8*, i8* }
+define dso_local void @func2(%struct.foo* %foo) sanitize_address {
+; CHECK-LABEL: @func2
+  tail call void @func1(%struct.foo* byval(%struct.foo) align 8 %foo) #2
+; CHECK: call void @__asan_report_load
+  ret void
+; CHECK: ret void
+}
+declare dso_local void @func1(%struct.foo* byval(%struct.foo) align 8)
+
+!0 = !{i32 1, !"wchar_size", i32 4}