[llvm] [HWASan] remove incorrectly inferred attributes (PR #106565)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Florian Mayer (fmayer)

<details>
<summary>Changes</summary>

assume all functions used in a HWASan module potentially touch shadow
memory (and short granules).


---
Full diff: https://github.com/llvm/llvm-project/pull/106565.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp (+14-8) 
- (added) llvm/test/Instrumentation/HWAddressSanitizer/attrinfer.ll (+13) 


``````````diff
diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 95433a216b168d..15d836a18d64fd 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -598,6 +598,20 @@ void HWAddressSanitizer::initializeModule() {
   LLVM_DEBUG(dbgs() << "Init " << M.getName() << "\n");
   TargetTriple = Triple(M.getTargetTriple());
 
+  for (auto &F : M.functions()) {
+    // Remove memory attributes that are invalid with HWASan.
+    // HWASan checks read from shadow, which invalidates memory(argmem: *)
+    // Short granule checks on function arguments read from the argument memory
+    // (last byte of the granule), which invalidates writeonly.
+    //
+    // This is not only true for sanitized functions, because AttrInfer can
+    // infer those attributes on libc functions, which is not true if those
+    // are instrumented (Android) or intercepted.
+    F.removeFnAttr(llvm::Attribute::Memory);
+    for (auto &A : F.args())
+      A.removeAttr(llvm::Attribute::WriteOnly);
+  }
+
   // x86_64 currently has two modes:
   // - Intel LAM (default)
   // - pointer aliasing (heap only)
@@ -1622,14 +1636,6 @@ void HWAddressSanitizer::sanitizeFunction(Function &F,
 
   assert(!ShadowBase);
 
-  // Remove memory attributes that are about to become invalid.
-  // HWASan checks read from shadow, which invalidates memory(argmem: *)
-  // Short granule checks on function arguments read from the argument memory
-  // (last byte of the granule), which invalidates writeonly.
-  F.removeFnAttr(llvm::Attribute::Memory);
-  for (auto &A : F.args())
-    A.removeAttr(llvm::Attribute::WriteOnly);
-
   BasicBlock::iterator InsertPt = F.getEntryBlock().begin();
   IRBuilder<> EntryIRB(&F.getEntryBlock(), InsertPt);
   emitPrologue(EntryIRB,
diff --git a/llvm/test/Instrumentation/HWAddressSanitizer/attrinfer.ll b/llvm/test/Instrumentation/HWAddressSanitizer/attrinfer.ll
new file mode 100644
index 00000000000000..46a9bbb0a6d894
--- /dev/null
+++ b/llvm/test/Instrumentation/HWAddressSanitizer/attrinfer.ll
@@ -0,0 +1,13 @@
+; Standard library functions get inferred attributes, some of which are not
+; correct when building for HWASan.
+
+; RUN: opt < %s -passes=hwasan -S | FileCheck %s --check-prefixes=CHECK
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64--linux-android10000"
+
+declare float @frexpf(float noundef, ptr nocapture noundef) local_unnamed_addr #0
+
+attributes #0 = { mustprogress nofree nounwind willreturn memory(argmem: write) "frame-pointer"="non-leaf" "hwasan-abi"="interceptor" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+fix-cortex-a53-835769,+fp-armv8,+neon,+outline-atomics,+tagged-globals,+v8a" }
+
+; CHECK-NOT: memory(argmem: write)
\ No newline at end of file

``````````

</details>


https://github.com/llvm/llvm-project/pull/106565