1//===-- checksum_test.cpp ---------------------------------------*- 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#include "tests/scudo_unit_test.h"
10
11#include "checksum.h"
12
13#include <string.h>
14
15static scudo::u16 computeSoftwareChecksum(scudo::u32 Seed, scudo::uptr *Array,
16 scudo::uptr ArraySize) {
17 scudo::u16 Checksum = static_cast<scudo::u16>(Seed & 0xffff);
18 for (scudo::uptr I = 0; I < ArraySize; I++)
19 Checksum = scudo::computeBSDChecksum(Sum: Checksum, Data: Array[I]);
20 return Checksum;
21}
22
23static scudo::u16 computeHardwareChecksum(scudo::u32 Seed, scudo::uptr *Array,
24 scudo::uptr ArraySize) {
25 scudo::u32 Crc = Seed;
26 for (scudo::uptr I = 0; I < ArraySize; I++)
27 Crc = scudo::computeHardwareCRC32(Crc, Data: Array[I]);
28 return static_cast<scudo::u16>((Crc & 0xffff) ^ (Crc >> 16));
29}
30
31typedef scudo::u16 (*ComputeChecksum)(scudo::u32, scudo::uptr *, scudo::uptr);
32
33// This verifies that flipping bits in the data being checksummed produces a
34// different checksum. We do not use random data to avoid flakyness.
35template <ComputeChecksum F> static void verifyChecksumFunctionBitFlip() {
36 scudo::uptr Array[sizeof(scudo::u64) / sizeof(scudo::uptr)];
37 const scudo::uptr ArraySize = ARRAY_SIZE(Array);
38 memset(s: Array, c: 0xaa, n: sizeof(Array));
39 const scudo::u32 Seed = 0x41424343U;
40 const scudo::u16 Reference = F(Seed, Array, ArraySize);
41 scudo::u8 IdenticalChecksums = 0;
42 for (scudo::uptr I = 0; I < ArraySize; I++) {
43 for (scudo::uptr J = 0; J < SCUDO_WORDSIZE; J++) {
44 Array[I] ^= scudo::uptr{1} << J;
45 if (F(Seed, Array, ArraySize) == Reference)
46 IdenticalChecksums++;
47 Array[I] ^= scudo::uptr{1} << J;
48 }
49 }
50 // Allow for a couple of identical checksums over the whole set of flips.
51 EXPECT_LE(IdenticalChecksums, 2);
52}
53
54TEST(ScudoChecksumTest, ChecksumFunctions) {
55 verifyChecksumFunctionBitFlip<computeSoftwareChecksum>();
56 if (&scudo::computeHardwareCRC32 && scudo::hasHardwareCRC32())
57 verifyChecksumFunctionBitFlip<computeHardwareChecksum>();
58}
59

source code of compiler-rt/lib/scudo/standalone/tests/checksum_test.cpp