86 lines
3.1 KiB
C++
86 lines
3.1 KiB
C++
//===-- strstr_fuzz.cpp ---------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// Fuzzing test for llvm-libc strstr implementation.
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///
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//===----------------------------------------------------------------------===//
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#include "src/string/strlen.h"
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#include "src/string/strstr.h"
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#include <stddef.h>
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#include <stdint.h>
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// Simple loop to compare two strings up to a size n.
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static int simple_memcmp(const char *left, const char *right, size_t n) {
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for (; n && *left == *right; ++left, ++right, --n)
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;
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return n ? *left - *right : 0;
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}
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// The general structure is to take the value of the first byte, set size1 to
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// that value, and add the null terminator. size2 will then contain the rest of
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// the bytes in data.
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// For example, with inputs (data={2, 6, 4, 8, 0}, size=5):
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// size1: data[0] = 2
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// data1: {2, 6} + '\0' = {2, 6, '\0'}
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// size2: size - size1 = 3
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// data2: {4, 8, '\0'}
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
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// Verify the size is at least 1 and the data is null terminated.
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if (!size || data[size - 1] != '\0')
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return 0;
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const size_t size1 = (data[0] <= size ? data[0] : size);
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// The first size will always be at least 1 since
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// we need to append the null terminator. The second size
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// needs to be checked since it must also contain the null
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// terminator.
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if (size - size1 == 0)
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return 0;
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// Copy the data into a new container.
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uint8_t *container = new uint8_t[size1 + 1];
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if (!container)
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__builtin_trap();
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size_t i;
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for (i = 0; i < size1; ++i)
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container[i] = data[i];
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container[size1] = '\0'; // Add null terminator to container.
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const char *needle = reinterpret_cast<const char *>(container);
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const char *haystack = reinterpret_cast<const char *>(data + i);
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const char *result = __llvm_libc::strstr(haystack, needle);
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// A null terminator may exist earlier in each, so this needs to be recorded.
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const size_t haystack_size = __llvm_libc::strlen(haystack);
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const size_t needle_size = __llvm_libc::strlen(needle);
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if (result) {
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// The needle is in the haystack.
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// 1. Verify that the result matches the needle.
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if (simple_memcmp(needle, result, needle_size) != 0)
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__builtin_trap();
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const char *haystack_ptr = haystack;
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// 2. Verify that the result is the first occurrence of the needle.
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for (; haystack_ptr != result; ++haystack_ptr) {
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if (simple_memcmp(needle, haystack_ptr, needle_size) == 0)
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__builtin_trap(); // There was an earlier occurrence of the needle.
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}
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} else {
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// No result was found. Verify that the needle doesn't exist within the
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// haystack.
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for (size_t i = 0; i + needle_size < haystack_size; ++i) {
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if (simple_memcmp(needle, haystack + i, needle_size) == 0)
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__builtin_trap(); // There was an earlier occurrence of the needle.
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}
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}
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delete[] container;
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return 0;
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}
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