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
computeSoftwareChecksum(scudo::u32 Seed,scudo::uptr * Array,scudo::uptr ArraySize)15 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(Checksum, Array[I]);
20 return Checksum;
21 }
22
computeHardwareChecksum(scudo::u32 Seed,scudo::uptr * Array,scudo::uptr ArraySize)23 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, Array[I]);
28 return static_cast<scudo::u16>((Crc & 0xffff) ^ (Crc >> 16));
29 }
30
31 typedef 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.
verifyChecksumFunctionBitFlip()35 template <ComputeChecksum F> void verifyChecksumFunctionBitFlip() {
36 scudo::uptr Array[sizeof(scudo::u64) / sizeof(scudo::uptr)];
37 const scudo::uptr ArraySize = ARRAY_SIZE(Array);
38 memset(Array, 0xaa, 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] ^= 1U << J;
45 if (F(Seed, Array, ArraySize) == Reference)
46 IdenticalChecksums++;
47 Array[I] ^= 1U << J;
48 }
49 }
50 // Allow for a couple of identical checksums over the whole set of flips.
51 EXPECT_LE(IdenticalChecksums, 2);
52 }
53
TEST(ScudoChecksumTest,ChecksumFunctions)54 TEST(ScudoChecksumTest, ChecksumFunctions) {
55 verifyChecksumFunctionBitFlip<computeSoftwareChecksum>();
56 if (&scudo::computeHardwareCRC32 && scudo::hasHardwareCRC32())
57 verifyChecksumFunctionBitFlip<computeHardwareChecksum>();
58 }
59