1 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
2 // See https://llvm.org/LICENSE.txt for license information.
3 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
4 
5 // Triggers the bug described here:
6 // https://github.com/google/oss-fuzz/issues/4605
7 //
8 // Tests that custom mutators do not cause MSan false positives.  We are careful
9 // to use every parameter to ensure none cause false positives.
10 
11 #include <algorithm>
12 #include <cstddef>
13 #include <cstdint>
14 #include <cstdio>
15 #include <cstring>
16 
17 extern "C" {
18 
19 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) { return 0; }
20 
21 size_t LLVMFuzzerCustomMutator(uint8_t *Data, size_t Size, size_t MaxSize,
22                                unsigned int Seed) {
23   if (Seed == 7)
24     return 0;
25   if (MaxSize == 0)
26     return 0;
27   for (size_t I = 0; I < Size; ++I) {
28     if (Data[I] == 42) {
29       printf("BINGO\n");
30     }
31   }
32   return Size;
33 }
34 
35 size_t LLVMFuzzerCustomCrossOver(
36     const uint8_t *Data1, size_t Size1, const uint8_t *Data2, size_t Size2,
37     uint8_t *Out, size_t MaxOutSize, unsigned int Seed) {
38   if (Seed == 7)
39     return 0;
40   size_t I = 0;
41   for (; I < Size1 && I < Size2 && I < MaxOutSize; ++I) {
42     Out[I] = std::min(Data1[I], Data2[I]);
43   }
44   return I;
45 }
46 
47 } // extern "C"
48