[hwasan] Fix allocator alignment.

[eugenis]

Summary

Fix hwasan allocator not respecting the requested alignment when it is
higher than a page, but still within primary (i.e. [2048, 65536]).

[cryptoad]

compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary64.h

79–83

Since we had the discussion, I understand the need to be aligned, but maybe a comment to clarify why for later readers?

compiler-rt/lib/sanitizer_common/sanitizer_common.cpp

328 ↗

(On Diff #262979)

Maybe a safe guard check that align is a power of 2?
With SizeClassMap::kMaxSize it's the case, but if it's used somewhere else, it might slip through.

[eugenis]

address comments

[eugenis]

One more CHECK + fix a broken test.

compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary64.h

public:
   }
   uptr CompactPtrToPointer(uptr base, CompactPtrT ptr32) const {
     return base + (static_cast<uptr>(ptr32) << kCompactPtrScale);
   }
 
   void Init(s32 release_to_os_interval_ms) {
     uptr TotalSpaceSize = kSpaceSize + AdditionalSize();
     if (kUsingConstantSpaceBeg) {
+      CHECK(IsAligned(kSpaceBeg, SizeClassMap::kMaxSize));
       CHECK_EQ(kSpaceBeg, address_range.Init(TotalSpaceSize,
                                              PrimaryAllocatorName, kSpaceBeg));
     } else {
-      NonConstSpaceBeg = address_range.Init(TotalSpaceSize,
-                                            PrimaryAllocatorName);
+      // Combined allocator expects that an 2^N allocation is always aligned to
+      // 2^N. For this to work, the start of the space needs to be aligned as
+      // high as the largest size class (which also needs to be a power of 2).
+      NonConstSpaceBeg = address_range.InitAligned(
+          TotalSpaceSize, SizeClassMap::kMaxSize, PrimaryAllocatorName);
       CHECK_NE(NonConstSpaceBeg, ~(uptr)0);
     }
     SetReleaseToOSIntervalMs(release_to_os_interval_ms);
     MapWithCallbackOrDie(SpaceEnd(), AdditionalSize(),
                          "SizeClassAllocator: region info");
     // Check that the RegionInfo array is aligned on the CacheLine size.
     DCHECK_EQ(SpaceEnd() % kCacheLineSize, 0);
   }
uptr TotalMemoryUsed() {
     uptr res = 0;
     for (uptr i = 0; i < kNumClasses; i++)
       res += GetRegionInfo(i)->allocated_user;
     return res;
   }
 
   // Test-only.
   void TestOnlyUnmap() {
-    UnmapWithCallbackOrDie(SpaceBeg(), kSpaceSize + AdditionalSize());
+    UnmapWithCallbackOrDie((uptr)address_range.base(), address_range.size());
   }
 
   static void FillMemoryProfile(uptr start, uptr rss, bool file, uptr *stats,
                            uptr stats_size) {
     for (uptr class_id = 0; class_id < stats_size; class_id++)
       if (stats[class_id] == start)
         stats[class_id] = rss;
   }

compiler-rt/lib/sanitizer_common/sanitizer_common.h

 // Check if the built VMA size matches the runtime one.
 void CheckVMASize();
 void RunMallocHooks(const void *ptr, uptr size);
 void RunFreeHooks(const void *ptr);
 
 class ReservedAddressRange {
  public:
   uptr Init(uptr size, const char *name = nullptr, uptr fixed_addr = 0);
+  uptr InitAligned(uptr size, uptr align, const char *name = nullptr);
   uptr Map(uptr fixed_addr, uptr size, const char *name = nullptr);
   uptr MapOrDie(uptr fixed_addr, uptr size, const char *name = nullptr);
   void Unmap(uptr addr, uptr size);
   void *base() const { return base_; }
   uptr size() const { return size_; }
 
  private:
   void* base_;

compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp

 #endif
 }
 
 static void (*sandboxing_callback)();
 void SetSandboxingCallback(void (*f)()) {
   sandboxing_callback = f;
 }
 
+uptr ReservedAddressRange::InitAligned(uptr size, uptr align,
+                                       const char *name) {
+  CHECK(IsPowerOfTwo(align));
+  if (align <= GetPageSizeCached())
+    return Init(size, name);
+  uptr start = Init(size + align, name);
+  start += align - (start & (align - 1));
+  return start;
+}
+
 }  // namespace __sanitizer
 
 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_sandbox_on_notify,
                              __sanitizer_sandbox_arguments *args) {
   __sanitizer::PlatformPrepareForSandboxing(args);
   if (__sanitizer::sandboxing_callback)
     __sanitizer::sandboxing_callback();
 }

compiler-rt/lib/sanitizer_common/tests/sanitizer_allocator_test.cpp

TEST(SanitizerCommon, LargeMmapAllocatorBlockBegin) {
   for (uptr i = 0; i < kNumAllocs; i++)
     a.Deallocate(&stats, allocated[i]);
 }
 
 
 // Don't test OOM conditions on Win64 because it causes other tests on the same
 // machine to OOM.
 #if SANITIZER_CAN_USE_ALLOCATOR64 && !SANITIZER_WINDOWS64 && !SANITIZER_ANDROID
-typedef __sanitizer::SizeClassMap<3, 4, 8, 63, 128, 16> SpecialSizeClassMap;
+typedef __sanitizer::SizeClassMap<3, 4, 8, 38, 128, 16> SpecialSizeClassMap;
 template <typename AddressSpaceViewTy = LocalAddressSpaceView>
 struct AP64_SpecialSizeClassMap {
   static const uptr kSpaceBeg = kAllocatorSpace;
   static const uptr kSpaceSize = kAllocatorSize;
   static const uptr kMetadataSize = 0;
   typedef SpecialSizeClassMap SizeClassMap;
   typedef NoOpMapUnmapCallback MapUnmapCallback;
   static const uptr kFlags = 0;

compiler-rt/test/hwasan/TestCases/malloc-align.c

+// Test malloc alignment.
+// RUN: %clang_hwasan -mllvm -hwasan-globals=0 %s -o %t
+// RUN: %run %t
+
+#include <assert.h>
+#include <sanitizer/allocator_interface.h>
+#include <sanitizer/hwasan_interface.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static const size_t sizes[] = {
+    1, 3, 7, 8, 9, 16, 17, 31, 32, 33,
+    63, 64, 65, 127, 128, 129, 511, 512, 513, 2047,
+    2048, 2049, 65535, 65536, 65537, 1048575, 1048576, 1048577};
+static const size_t alignments[] = {8, 16, 64, 256, 1024, 4096, 65536, 131072};
+
+__attribute__((no_sanitize("hwaddress"))) int main() {
+  for (unsigned i = 0; i < sizeof(sizes) / sizeof(*sizes); ++i) {
+    for (unsigned j = 0; j < sizeof(alignments) / sizeof(*alignments); ++j) {
+      size_t size = sizes[i];
+      size_t alignment = alignments[j];
+      fprintf(stderr, "size %zu, alignment %zu (0x%zx)\n", size, alignment,
+              alignment);
+      const int cnt = 10;
+      void *ptrs[cnt];
+      for (int k = 0; k < cnt; ++k) {
+        int res = posix_memalign(&ptrs[k], alignment, size);
+        assert(res == 0);
+        fprintf(stderr, "... addr 0x%zx\n", (size_t)ptrs[k]);
+        assert(((size_t)ptrs[k] & (alignment - 1)) == 0);
+      }
+      for (int k = 0; k < cnt; ++k)
+        free(ptrs[k]);
+    }
+  }
+  return 0;
+}