1  //===-- hwasan_malloc_bisect.h ----------------------------------*- C++ -*-===//
       2  //
       3  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
       4  // See https://llvm.org/LICENSE.txt for license information.
       5  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
       6  //
       7  //===----------------------------------------------------------------------===//
       8  //
       9  // This file is a part of HWAddressSanitizer.
      10  //
      11  //===----------------------------------------------------------------------===//
      12  
      13  #include "sanitizer_common/sanitizer_hash.h"
      14  #include "hwasan.h"
      15  
      16  namespace __hwasan {
      17  
      18  static u32 malloc_hash(StackTrace *stack, uptr orig_size) {
      19    uptr len = Min(stack->size, (unsigned)7);
      20    MurMur2HashBuilder H(len);
      21    H.add(orig_size);
      22    // Start with frame #1 to skip __sanitizer_malloc frame, which is
      23    // (a) almost always the same (well, could be operator new or new[])
      24    // (b) can change hashes when compiler-rt is rebuilt, invalidating previous
      25    // bisection results.
      26    // Because of ASLR, use only offset inside the page.
      27    for (uptr i = 1; i < len; ++i) H.add(((u32)stack->trace[i]) & 0xFFF);
      28    return H.get();
      29  }
      30  
      31  static inline bool malloc_bisect(StackTrace *stack, uptr orig_size) {
      32    uptr left = flags()->malloc_bisect_left;
      33    uptr right = flags()->malloc_bisect_right;
      34    if (LIKELY(left == 0 && right == 0))
      35      return true;
      36    if (!stack)
      37      return true;
      38    // Allow malloc_bisect_right > (u32)(-1) to avoid spelling the latter in
      39    // decimal.
      40    uptr h = (uptr)malloc_hash(stack, orig_size);
      41    if (h < left || h > right)
      42      return false;
      43    if (flags()->malloc_bisect_dump) {
      44      Printf("[alloc] %u %zu\n", h, orig_size);
      45      stack->Print();
      46    }
      47    return true;
      48  }
      49  
      50  }  // namespace __hwasan