[PATCH] D77613: [AddressSanitizer] Instrument byval call arguments

[Jann Horn via Phabricator via llvm-commits]

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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.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77613

Files:
  llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
  llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
  llvm/test/Instrumentation/AddressSanitizer/byval-args.ll


Index: llvm/test/Instrumentation/AddressSanitizer/byval-args.ll
===================================================================
--- /dev/null
+++ llvm/test/Instrumentation/AddressSanitizer/byval-args.ll
@@ -0,0 +1,18 @@
+; 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}
Index: llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -548,6 +548,13 @@
       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);
+    }
   }
 }
 
Index: llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1415,6 +1415,14 @@
         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);
+      }
     }
   }
 }


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