| 1 | //===- FuzzerExtraCountersWindows.cpp - Extra coverage counters for Win32 -===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // Extra coverage counters defined by user code for Windows. |
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| 9 | //===----------------------------------------------------------------------===// |
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| 10 | |
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| 11 | #include "FuzzerPlatform.h" |
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| 12 | #include <cstdint> |
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| 13 | |
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| 14 | #if LIBFUZZER_WINDOWS |
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| 15 | #include <windows.h> |
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| 16 | |
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| 17 | namespace fuzzer { |
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| 18 | |
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| 19 | // |
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| 20 | // The __start___libfuzzer_extra_counters variable is align 16, size 16 to |
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| 21 | // ensure the padding between it and the next variable in this section (either |
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| 22 | // __libfuzzer_extra_counters or __stop___libfuzzer_extra_counters) will be |
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| 23 | // located at (__start___libfuzzer_extra_counters + |
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| 24 | // sizeof(__start___libfuzzer_extra_counters)). Otherwise, the calculation of |
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| 25 | // (stop - (start + sizeof(start))) might be skewed. |
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| 26 | // |
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| 27 | // The section name, __libfuzzer_extra_countaaa ends with "aaa", so it sorts |
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| 28 | // before __libfuzzer_extra_counters alphabetically. We want the start symbol to |
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| 29 | // be placed in the section just before the user supplied counters (if present). |
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| 30 | // |
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| 31 | #pragma section(".data$__libfuzzer_extra_countaaa") |
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| 32 | ATTRIBUTE_ALIGNED(16) |
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| 33 | __declspec(allocate(".data$__libfuzzer_extra_countaaa" )) uint8_t |
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| 34 | __start___libfuzzer_extra_counters[16] = {0}; |
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| 35 | |
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| 36 | // |
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| 37 | // Example of what the user-supplied counters should look like. First, the |
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| 38 | // pragma to create the section name. It will fall alphabetically between |
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| 39 | // ".data$__libfuzzer_extra_countaaa" and ".data$__libfuzzer_extra_countzzz". |
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| 40 | // Next, the declspec to allocate the variable inside the specified section. |
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| 41 | // Finally, some array, struct, whatever that is used to track the counter data. |
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| 42 | // The size of this variable is computed at runtime by finding the difference of |
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| 43 | // __stop___libfuzzer_extra_counters and __start___libfuzzer_extra_counters + |
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| 44 | // sizeof(__start___libfuzzer_extra_counters). |
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| 45 | // |
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| 46 | |
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| 47 | // |
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| 48 | // #pragma section(".data$__libfuzzer_extra_counters") |
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| 49 | // __declspec(allocate(".data$__libfuzzer_extra_counters")) |
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| 50 | // uint8_t any_name_variable[64 * 1024]; |
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| 51 | // |
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| 52 | |
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| 53 | // |
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| 54 | // Here, the section name, __libfuzzer_extra_countzzz ends with "zzz", so it |
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| 55 | // sorts after __libfuzzer_extra_counters alphabetically. We want the stop |
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| 56 | // symbol to be placed in the section just after the user supplied counters (if |
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| 57 | // present). Align to 1 so there isn't any padding placed between this and the |
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| 58 | // previous variable. |
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| 59 | // |
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| 60 | #pragma section(".data$__libfuzzer_extra_countzzz") |
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| 61 | ATTRIBUTE_ALIGNED(1) |
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| 62 | __declspec(allocate(".data$__libfuzzer_extra_countzzz" )) uint8_t |
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| 63 | __stop___libfuzzer_extra_counters = 0; |
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| 64 | |
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| 65 | uint8_t *ExtraCountersBegin() { |
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| 66 | return __start___libfuzzer_extra_counters + |
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| 67 | sizeof(__start___libfuzzer_extra_counters); |
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| 68 | } |
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| 69 | |
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| 70 | uint8_t *ExtraCountersEnd() { return &__stop___libfuzzer_extra_counters; } |
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| 71 | |
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| 72 | ATTRIBUTE_NO_SANITIZE_ALL |
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| 73 | void ClearExtraCounters() { |
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| 74 | uint8_t *Beg = ExtraCountersBegin(); |
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| 75 | SecureZeroMemory(Beg, ExtraCountersEnd() - Beg); |
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| 76 | } |
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| 77 | |
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| 78 | } // namespace fuzzer |
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| 79 | |
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| 80 | #endif |
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| 81 | |
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