[Asan] Accept __lsan_ignore_object for redzone pointer

[vitalybuka]

Summary

The check that the pointer inside of the user part of the chunk does not
adds any value, but it's the last user of AddrIsInside.

I'd like to simplify AsanChunk in followup patches.

[morehouse]

LGTM

compiler-rt/lib/asan/asan_allocator.cpp

void *AllocBeg(bool locked_version = false) {
     if (from_memalign) {
       if (locked_version)
         return get_allocator().GetBlockBeginFastLocked(
             reinterpret_cast<void *>(this));
       return get_allocator().GetBlockBegin(reinterpret_cast<void *>(this));
     }
     return reinterpret_cast<void*>(Beg() - RZLog2Size(rz_log));
   }
-  bool AddrIsInside(uptr addr, bool locked_version = false) {
-    return (addr >= Beg()) && (addr < Beg() + UsedSize(locked_version));
-  }
 };
 
 struct QuarantineCallback {
   QuarantineCallback(AllocatorCache *cache, BufferedStackTrace *stack)
       : cache_(cache),
         stack_(stack) {
   }
 

 
 void ForEachChunk(ForEachChunkCallback callback, void *arg) {
   __asan::get_allocator().ForEachChunk(callback, arg);
 }
 
 IgnoreObjectResult IgnoreObjectLocked(const void *p) {
   uptr addr = reinterpret_cast<uptr>(p);
   __asan::AsanChunk *m = __asan::instance.GetAsanChunkByAddr(addr);
-  if (!m) return kIgnoreObjectInvalid;
-  if ((atomic_load(&m->chunk_state, memory_order_acquire) ==
-       __asan::CHUNK_ALLOCATED) &&
-      m->AddrIsInside(addr)) {
-    if (m->lsan_tag == kIgnored)
-      return kIgnoreObjectAlreadyIgnored;
-    m->lsan_tag = __lsan::kIgnored;
-    return kIgnoreObjectSuccess;
-  }
-  return kIgnoreObjectInvalid;
-}
+  if (!m || (atomic_load(&m->chunk_state, memory_order_acquire) !=
+             __asan::CHUNK_ALLOCATED)) {
+    return kIgnoreObjectInvalid;
+  }
 }  // namespace __lsan
 
 // ---------------------- Interface ---------------- {{{1
 using namespace __asan;
 
 // ASan allocator doesn't reserve extra bytes, so normally we would
 // just return "size". We don't want to expose our redzone sizes, etc here.
 uptr __sanitizer_get_estimated_allocated_size(uptr size) {

compiler-rt/test/asan/TestCases/lsan_annotations.cpp

 // Check that LSan annotations work fine.
 // RUN: %clangxx_asan -O0 %s -o %t && %run %t
 // RUN: %clangxx_asan -O3 %s -o %t && %run %t
 
 #include <sanitizer/lsan_interface.h>
 #include <stdlib.h>
 
+int *x, *y, *z;
+
 int main() {
-  int *x = new int;
+  x = new int;
   __lsan_ignore_object(x);
+
   {
     __lsan::ScopedDisabler disabler;
-    double *y = new double;
+    y = new int;
   }
+
+  z = new int;
+  __lsan_ignore_object(z - 1);
+
+  x = y = z = nullptr;
   return 0;
 }