asan_malloc_win.cpp

//===-- asan_malloc_win.cpp -----------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
//
// Windows-specific malloc interception.
//===----------------------------------------------------------------------===//

#include "sanitizer_common/sanitizer_allocator_interface.h"
#include "sanitizer_common/sanitizer_platform.h"
#if SANITIZER_WINDOWS
#include "asan_allocator.h"
#include "asan_interceptors.h"
#include "asan_internal.h"
#include "asan_stack.h"
#include "interception/interception.h"
#include <stddef.h>

// Intentionally not including windows.h here, to avoid the risk of
// pulling in conflicting declarations of these functions. (With mingw-w64,
// there's a risk of windows.h pulling in stdint.h.)
typedef int BOOL;
typedef void *HANDLE;
typedef const void *LPCVOID;
typedef void *LPVOID;

typedef unsigned long DWORD;
constexpr unsigned long HEAP_ZERO_MEMORY = 0x00000008;
constexpr unsigned long HEAP_REALLOC_IN_PLACE_ONLY = 0x00000010;
constexpr unsigned long HEAP_ALLOCATE_SUPPORTED_FLAGS = (HEAP_ZERO_MEMORY);
constexpr unsigned long HEAP_ALLOCATE_UNSUPPORTED_FLAGS =
    (~HEAP_ALLOCATE_SUPPORTED_FLAGS);
constexpr unsigned long HEAP_FREE_UNSUPPORTED_FLAGS =
    (~HEAP_ALLOCATE_SUPPORTED_FLAGS);
constexpr unsigned long HEAP_REALLOC_UNSUPPORTED_FLAGS =
    (~HEAP_ALLOCATE_SUPPORTED_FLAGS);


extern "C" {
LPVOID WINAPI HeapAlloc(HANDLE hHeap, DWORD dwFlags, size_t dwBytes);
LPVOID WINAPI HeapReAlloc(HANDLE hHeap, DWORD dwFlags, LPVOID lpMem,
                         size_t dwBytes);
BOOL WINAPI HeapFree(HANDLE hHeap, DWORD dwFlags, LPVOID lpMem);
size_t WINAPI HeapSize(HANDLE hHeap, DWORD dwFlags, LPCVOID lpMem);

BOOL WINAPI HeapValidate(HANDLE hHeap, DWORD dwFlags, LPCVOID lpMem);
}

using namespace __asan;

// MT: Simply defining functions with the same signature in *.obj
// files overrides the standard functions in the CRT.
// MD: Memory allocation functions are defined in the CRT .dll,
// so we have to intercept them before they are called for the first time.

#if ASAN_DYNAMIC
# define ALLOCATION_FUNCTION_ATTRIBUTE
#else
# define ALLOCATION_FUNCTION_ATTRIBUTE SANITIZER_INTERFACE_ATTRIBUTE
#endif

extern "C" {
ALLOCATION_FUNCTION_ATTRIBUTE
size_t _msize(void *ptr) {
  GET_CURRENT_PC_BP_SP;
  (void)sp;
  return asan_malloc_usable_size(ptr, pc, bp);
}

ALLOCATION_FUNCTION_ATTRIBUTE
size_t _msize_base(void *ptr) {
  return _msize(ptr);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void free(void *ptr) {
  GET_STACK_TRACE_FREE;
  return asan_free(ptr, &stack, FROM_MALLOC);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void _free_dbg(void *ptr, int) {
  free(ptr);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void _free_base(void *ptr) {
  free(ptr);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *malloc(size_t size) {
  GET_STACK_TRACE_MALLOC;
  return asan_malloc(size, &stack);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_malloc_base(size_t size) {
  return malloc(size);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_malloc_dbg(size_t size, int, const char *, int) {
  return malloc(size);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *calloc(size_t nmemb, size_t size) {
  GET_STACK_TRACE_MALLOC;
  return asan_calloc(nmemb, size, &stack);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_calloc_base(size_t nmemb, size_t size) {
  return calloc(nmemb, size);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_calloc_dbg(size_t nmemb, size_t size, int, const char *, int) {
  return calloc(nmemb, size);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_calloc_impl(size_t nmemb, size_t size, int *errno_tmp) {
  return calloc(nmemb, size);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *realloc(void *ptr, size_t size) {
  GET_STACK_TRACE_MALLOC;
  return asan_realloc(ptr, size, &stack);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_realloc_dbg(void *ptr, size_t size, int) {
  UNREACHABLE("_realloc_dbg should not exist!");
  return 0;
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_realloc_base(void *ptr, size_t size) {
  return realloc(ptr, size);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_recalloc(void *p, size_t n, size_t elem_size) {
  if (!p)
    return calloc(n, elem_size);
  const size_t size = n * elem_size;
  if (elem_size != 0 && size / elem_size != n)
    return 0;

  size_t old_size = _msize(p);
  void *new_alloc = malloc(size);
  if (new_alloc) {
    REAL(memcpy)(new_alloc, p, Min<size_t>(size, old_size));
    if (old_size < size)
      REAL(memset)(((u8 *)new_alloc) + old_size, 0, size - old_size);
    free(p);
  }
  return new_alloc;
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_recalloc_base(void *p, size_t n, size_t elem_size) {
  return _recalloc(p, n, elem_size);
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_expand(void *memblock, size_t size) {
  // _expand is used in realloc-like functions to resize the buffer if possible.
  // We don't want memory to stand still while resizing buffers, so return 0.
  return 0;
}

ALLOCATION_FUNCTION_ATTRIBUTE
void *_expand_dbg(void *memblock, size_t size) {
  return _expand(memblock, size);
}

// TODO(timurrrr): Might want to add support for _aligned_* allocation
// functions to detect a bit more bugs.  Those functions seem to wrap malloc().

int _CrtDbgReport(int, const char*, int,
                  const char*, const char*, ...) {
  ShowStatsAndAbort();
}

int _CrtDbgReportW(int reportType, const wchar_t*, int,
                   const wchar_t*, const wchar_t*, ...) {
  ShowStatsAndAbort();
}

int _CrtSetReportMode(int, int) {
  return 0;
}
}  // extern "C"

#define OWNED_BY_RTL(heap, memory) \
  (!__sanitizer_get_ownership(memory) && HeapValidate(heap, 0, memory))

INTERCEPTOR_WINAPI(size_t, HeapSize, HANDLE hHeap, DWORD dwFlags,
                   LPCVOID lpMem) {
  // If the RTL allocators are hooked we need to check whether the ASAN
  // allocator owns the pointer we're about to use. Allocations occur before
  // interception takes place, so if it is not owned by the RTL heap we can
  // pass it to the ASAN heap for inspection.
  if (flags()->windows_hook_rtl_allocators) {
    if (!asan_inited || OWNED_BY_RTL(hHeap, lpMem))
      return REAL(HeapSize)(hHeap, dwFlags, lpMem);
  } else {
    CHECK(dwFlags == 0 && "unsupported heap flags");
  }
  GET_CURRENT_PC_BP_SP;
  (void)sp;
  return asan_malloc_usable_size(lpMem, pc, bp);
}

INTERCEPTOR_WINAPI(LPVOID, HeapAlloc, HANDLE hHeap, DWORD dwFlags,
                   size_t dwBytes) {
  // If the ASAN runtime is not initialized, or we encounter an unsupported
  // flag, fall back to the original allocator.
  if (flags()->windows_hook_rtl_allocators) {
    if (UNLIKELY(!asan_inited ||
                 (dwFlags & HEAP_ALLOCATE_UNSUPPORTED_FLAGS) != 0)) {
      return REAL(HeapAlloc)(hHeap, dwFlags, dwBytes);
    }
  } else {
    // In the case that we don't hook the rtl allocators,
    // this becomes an assert since there is no failover to the original
    // allocator.
    CHECK((HEAP_ALLOCATE_UNSUPPORTED_FLAGS & dwFlags) != 0 &&
          "unsupported flags");
  }
  GET_STACK_TRACE_MALLOC;
  void *p = asan_malloc(dwBytes, &stack);
  // Reading MSDN suggests that the *entire* usable allocation is zeroed out.
  // Otherwise it is difficult to HeapReAlloc with HEAP_ZERO_MEMORY.
  // https://blogs.msdn.microsoft.com/oldnewthing/20120316-00/?p=8083
  if (p && (dwFlags & HEAP_ZERO_MEMORY)) {
    GET_CURRENT_PC_BP_SP;
    (void)sp;
    auto usable_size = asan_malloc_usable_size(p, pc, bp);
    internal_memset(p, 0, usable_size);
  }
  return p;
}

INTERCEPTOR_WINAPI(BOOL, HeapFree, HANDLE hHeap, DWORD dwFlags, LPVOID lpMem) {
  // Heap allocations happen before this function is hooked, so we must fall
  // back to the original function if the pointer is not from the ASAN heap,
  // or unsupported flags are provided.
  if (flags()->windows_hook_rtl_allocators) {
    if (OWNED_BY_RTL(hHeap, lpMem))
      return REAL(HeapFree)(hHeap, dwFlags, lpMem);
  } else {
    CHECK((HEAP_FREE_UNSUPPORTED_FLAGS & dwFlags) != 0 && "unsupported flags");
  }
  GET_STACK_TRACE_FREE;
  asan_free(lpMem, &stack, FROM_MALLOC);
  return true;
}

namespace __asan {
using AllocFunction = LPVOID(WINAPI *)(HANDLE, DWORD, size_t);
using ReAllocFunction = LPVOID(WINAPI *)(HANDLE, DWORD, LPVOID, size_t);
using SizeFunction = size_t(WINAPI *)(HANDLE, DWORD, LPVOID);
using FreeFunction = BOOL(WINAPI *)(HANDLE, DWORD, LPVOID);

void *SharedReAlloc(ReAllocFunction reallocFunc, SizeFunction heapSizeFunc,
                    FreeFunction freeFunc, AllocFunction allocFunc,
                    HANDLE hHeap, DWORD dwFlags, LPVOID lpMem, size_t dwBytes) {
  CHECK(reallocFunc && heapSizeFunc && freeFunc && allocFunc);
  GET_STACK_TRACE_MALLOC;
  GET_CURRENT_PC_BP_SP;
  (void)sp;
  if (flags()->windows_hook_rtl_allocators) {
    enum AllocationOwnership { NEITHER = 0, ASAN = 1, RTL = 2 };
    AllocationOwnership ownershipState;
    bool owned_rtlalloc = false;
    bool owned_asan = __sanitizer_get_ownership(lpMem);

    if (!owned_asan)
      owned_rtlalloc = HeapValidate(hHeap, 0, lpMem);

    if (owned_asan && !owned_rtlalloc)
      ownershipState = ASAN;
    else if (!owned_asan && owned_rtlalloc)
      ownershipState = RTL;
    else if (!owned_asan && !owned_rtlalloc)
      ownershipState = NEITHER;

    // If this heap block which was allocated before the ASAN
    // runtime came up, use the real HeapFree function.
    if (UNLIKELY(!asan_inited)) {
      return reallocFunc(hHeap, dwFlags, lpMem, dwBytes);
    }
    bool only_asan_supported_flags =
        (HEAP_REALLOC_UNSUPPORTED_FLAGS & dwFlags) == 0;

    if (ownershipState == RTL ||
        (ownershipState == NEITHER && !only_asan_supported_flags)) {
      if (only_asan_supported_flags) {
        // if this is a conversion to ASAN upported flags, transfer this
        // allocation to the ASAN allocator
        void *replacement_alloc;
        if (dwFlags & HEAP_ZERO_MEMORY)
          replacement_alloc = asan_calloc(1, dwBytes, &stack);
        else
          replacement_alloc = asan_malloc(dwBytes, &stack);
        if (replacement_alloc) {
          size_t old_size = heapSizeFunc(hHeap, dwFlags, lpMem);
          if (old_size == ((size_t)0) - 1) {
            asan_free(replacement_alloc, &stack, FROM_MALLOC);
            return nullptr;
          }
          REAL(memcpy)(replacement_alloc, lpMem, old_size);
          freeFunc(hHeap, dwFlags, lpMem);
        }
        return replacement_alloc;
      } else {
        // owned by rtl or neither with unsupported ASAN flags,
        // just pass back to original allocator
        CHECK(ownershipState == RTL || ownershipState == NEITHER);
        CHECK(!only_asan_supported_flags);
        return reallocFunc(hHeap, dwFlags, lpMem, dwBytes);
      }
    }

    if (ownershipState == ASAN && !only_asan_supported_flags) {
      // Conversion to unsupported flags allocation,
      // transfer this allocation back to the original allocator.
      void *replacement_alloc = allocFunc(hHeap, dwFlags, dwBytes);
      size_t old_usable_size = 0;
      if (replacement_alloc) {
        old_usable_size = asan_malloc_usable_size(lpMem, pc, bp);
        REAL(memcpy)(replacement_alloc, lpMem,
                     Min<size_t>(dwBytes, old_usable_size));
        asan_free(lpMem, &stack, FROM_MALLOC);
      }
      return replacement_alloc;
    }

    CHECK((ownershipState == ASAN || ownershipState == NEITHER) &&
          only_asan_supported_flags);
    // At this point we should either be ASAN owned with ASAN supported flags
    // or we owned by neither and have supported flags.
    // Pass through even when it's neither since this could be a null realloc or
    // UAF that ASAN needs to catch.
  } else {
    CHECK((HEAP_REALLOC_UNSUPPORTED_FLAGS & dwFlags) != 0 &&
          "unsupported flags");
  }
  // asan_realloc will never reallocate in place, so for now this flag is
  // unsupported until we figure out a way to fake this.
  if (dwFlags & HEAP_REALLOC_IN_PLACE_ONLY)
    return nullptr;

  // HeapReAlloc and HeapAlloc both happily accept 0 sized allocations.
  // passing a 0 size into asan_realloc will free the allocation.
  // To avoid this and keep behavior consistent, fudge the size if 0.
  // (asan_malloc already does this)
  if (dwBytes == 0)
    dwBytes = 1;

  size_t old_size;
  if (dwFlags & HEAP_ZERO_MEMORY)
    old_size = asan_malloc_usable_size(lpMem, pc, bp);

  void *ptr = asan_realloc(lpMem, dwBytes, &stack);
  if (ptr == nullptr)
    return nullptr;

  if (dwFlags & HEAP_ZERO_MEMORY) {
    size_t new_size = asan_malloc_usable_size(ptr, pc, bp);
    if (old_size < new_size)
      REAL(memset)(((u8 *)ptr) + old_size, 0, new_size - old_size);
  }

  return ptr;
}
}  // namespace __asan

INTERCEPTOR_WINAPI(LPVOID, HeapReAlloc, HANDLE hHeap, DWORD dwFlags,
                   LPVOID lpMem, size_t dwBytes) {
  return SharedReAlloc(REAL(HeapReAlloc), (SizeFunction)REAL(HeapSize),
                       REAL(HeapFree), REAL(HeapAlloc), hHeap, dwFlags, lpMem,
                       dwBytes);
}

// The following functions are undocumented and subject to change.
// However, hooking them is necessary to hook Windows heap
// allocations with detours and their definitions are unlikely to change.
// Comments in /minkernel/ntos/rtl/heappublic.c indicate that these functions
// are part of the heap's public interface.
typedef unsigned long LOGICAL;

// This function is documented as part of the Driver Development Kit but *not*
// the Windows Development Kit.
LOGICAL RtlFreeHeap(void* HeapHandle, DWORD Flags,
                            void* BaseAddress);

// This function is documented as part of the Driver Development Kit but *not*
// the Windows Development Kit.
void* RtlAllocateHeap(void* HeapHandle, DWORD Flags, size_t Size);

// This function is completely undocumented.
void*
RtlReAllocateHeap(void* HeapHandle, DWORD Flags, void* BaseAddress,
                  size_t Size);

// This function is completely undocumented.
size_t RtlSizeHeap(void* HeapHandle, DWORD Flags, void* BaseAddress);

INTERCEPTOR_WINAPI(size_t, RtlSizeHeap, HANDLE HeapHandle, DWORD Flags,
                   void* BaseAddress) {
  if (!flags()->windows_hook_rtl_allocators ||
      UNLIKELY(!asan_inited || OWNED_BY_RTL(HeapHandle, BaseAddress))) {
    return REAL(RtlSizeHeap)(HeapHandle, Flags, BaseAddress);
  }
  GET_CURRENT_PC_BP_SP;
  (void)sp;
  return asan_malloc_usable_size(BaseAddress, pc, bp);
}

INTERCEPTOR_WINAPI(BOOL, RtlFreeHeap, HANDLE HeapHandle, DWORD Flags,
                   void* BaseAddress) {
  // Heap allocations happen before this function is hooked, so we must fall
  // back to the original function if the pointer is not from the ASAN heap, or
  // unsupported flags are provided.
  if (!flags()->windows_hook_rtl_allocators ||
      UNLIKELY((HEAP_FREE_UNSUPPORTED_FLAGS & Flags) != 0 ||
               OWNED_BY_RTL(HeapHandle, BaseAddress))) {
    return REAL(RtlFreeHeap)(HeapHandle, Flags, BaseAddress);
  }
  GET_STACK_TRACE_FREE;
  asan_free(BaseAddress, &stack, FROM_MALLOC);
  return true;
}

INTERCEPTOR_WINAPI(void*, RtlAllocateHeap, HANDLE HeapHandle, DWORD Flags,
                   size_t Size) {
  // If the ASAN runtime is not initialized, or we encounter an unsupported
  // flag, fall back to the original allocator.
  if (!flags()->windows_hook_rtl_allocators ||
      UNLIKELY(!asan_inited ||
               (Flags & HEAP_ALLOCATE_UNSUPPORTED_FLAGS) != 0)) {
    return REAL(RtlAllocateHeap)(HeapHandle, Flags, Size);
  }
  GET_STACK_TRACE_MALLOC;
  void *p;
  // Reading MSDN suggests that the *entire* usable allocation is zeroed out.
  // Otherwise it is difficult to HeapReAlloc with HEAP_ZERO_MEMORY.
  // https://blogs.msdn.microsoft.com/oldnewthing/20120316-00/?p=8083
  if (Flags & HEAP_ZERO_MEMORY) {
    p = asan_calloc(Size, 1, &stack);
  } else {
    p = asan_malloc(Size, &stack);
  }
  return p;
}

INTERCEPTOR_WINAPI(void*, RtlReAllocateHeap, HANDLE HeapHandle, DWORD Flags,
                   void* BaseAddress, size_t Size) {
  // If it's actually a heap block which was allocated before the ASAN runtime
  // came up, use the real RtlFreeHeap function.
  if (!flags()->windows_hook_rtl_allocators)
    return REAL(RtlReAllocateHeap)(HeapHandle, Flags, BaseAddress, Size);

  return SharedReAlloc(REAL(RtlReAllocateHeap), REAL(RtlSizeHeap),
                       REAL(RtlFreeHeap), REAL(RtlAllocateHeap), HeapHandle,
                       Flags, BaseAddress, Size);
}

namespace __asan {

static void TryToOverrideFunction(const char *fname, uptr new_func) {
  // Failure here is not fatal. The CRT may not be present, and different CRT
  // versions use different symbols.
  if (!__interception::OverrideFunction(fname, new_func))
    VPrintf(2, "Failed to override function %s\n", fname);
}

void ReplaceSystemMalloc() {
#if defined(ASAN_DYNAMIC)
  TryToOverrideFunction("free", (uptr)free);
  TryToOverrideFunction("_free_base", (uptr)free);
  TryToOverrideFunction("malloc", (uptr)malloc);
  TryToOverrideFunction("_malloc_base", (uptr)malloc);
  TryToOverrideFunction("_malloc_crt", (uptr)malloc);
  TryToOverrideFunction("calloc", (uptr)calloc);
  TryToOverrideFunction("_calloc_base", (uptr)calloc);
  TryToOverrideFunction("_calloc_crt", (uptr)calloc);
  TryToOverrideFunction("realloc", (uptr)realloc);
  TryToOverrideFunction("_realloc_base", (uptr)realloc);
  TryToOverrideFunction("_realloc_crt", (uptr)realloc);
  TryToOverrideFunction("_recalloc", (uptr)_recalloc);
  TryToOverrideFunction("_recalloc_base", (uptr)_recalloc);
  TryToOverrideFunction("_recalloc_crt", (uptr)_recalloc);
  TryToOverrideFunction("_msize", (uptr)_msize);
  TryToOverrideFunction("_msize_base", (uptr)_msize);
  TryToOverrideFunction("_expand", (uptr)_expand);
  TryToOverrideFunction("_expand_base", (uptr)_expand);

  if (flags()->windows_hook_rtl_allocators) {
    INTERCEPT_FUNCTION(HeapSize);
    INTERCEPT_FUNCTION(HeapFree);
    INTERCEPT_FUNCTION(HeapReAlloc);
    INTERCEPT_FUNCTION(HeapAlloc);

    // Undocumented functions must be intercepted by name, not by symbol.
    __interception::OverrideFunction("RtlSizeHeap", (uptr)WRAP(RtlSizeHeap),
                                     (uptr *)&REAL(RtlSizeHeap));
    __interception::OverrideFunction("RtlFreeHeap", (uptr)WRAP(RtlFreeHeap),
                                     (uptr *)&REAL(RtlFreeHeap));
    __interception::OverrideFunction("RtlReAllocateHeap",
                                     (uptr)WRAP(RtlReAllocateHeap),
                                     (uptr *)&REAL(RtlReAllocateHeap));
    __interception::OverrideFunction("RtlAllocateHeap",
                                     (uptr)WRAP(RtlAllocateHeap),
                                     (uptr *)&REAL(RtlAllocateHeap));
  } else {
#define INTERCEPT_UCRT_FUNCTION(func)                                  \
  if (!INTERCEPT_FUNCTION_DLLIMPORT(                                   \
          "ucrtbase.dll", "api-ms-win-core-heap-l1-1-0.dll", func)) {  \
    VPrintf(2, "Failed to intercept ucrtbase.dll import %s\n", #func); \
  }
    INTERCEPT_UCRT_FUNCTION(HeapAlloc);
    INTERCEPT_UCRT_FUNCTION(HeapFree);
    INTERCEPT_UCRT_FUNCTION(HeapReAlloc);
    INTERCEPT_UCRT_FUNCTION(HeapSize);
#undef INTERCEPT_UCRT_FUNCTION
  }
  // Recent versions of ucrtbase.dll appear to be built with PGO and LTCG, which
  // enable cross-module inlining. This means our _malloc_base hook won't catch
  // all CRT allocations. This code here patches the import table of
  // ucrtbase.dll so that all attempts to use the lower-level win32 heap
  // allocation API will be directed to ASan's heap. We don't currently
  // intercept all calls to HeapAlloc. If we did, we would have to check on
  // HeapFree whether the pointer came from ASan of from the system.

#endif  // defined(ASAN_DYNAMIC)
}
}  // namespace __asan

#endif  // _WIN32