mirror of
https://github.com/RGBCube/serenity
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80 lines
2.6 KiB
C++
80 lines
2.6 KiB
C++
/*
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* Copyright (c) 2021, Ben Wiederhake <BenWiederhake.GitHub@gmx.de>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Assertions.h>
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#include <LibCore/ArgsParser.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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static void write8(void* ptr) { *(volatile uint8_t*)ptr = 1; }
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static void write16(void* ptr) { *(volatile uint16_t*)ptr = 1; }
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static void write32(void* ptr) { *(volatile uint32_t*)ptr = 1; }
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static void write64(void* ptr) { *(volatile double*)ptr = 1.0; }
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// A u64 write might be translated by the compiler as a 32-then-32-bit write:
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// static void write64_bad(void* ptr) { *(volatile uint64_t*)ptr = 1.0; }
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// Let's hope this won't be translated like that.
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// Godbolt says yes: https://godbolt.org/z/1b9WGo
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static void run_test(void* region, ssize_t offset, size_t bits)
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{
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void* ptr = (char*)region + offset;
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printf("Writing to %p\n", ptr);
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switch (bits) {
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case 8:
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write8(ptr);
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break;
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case 16:
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write16(ptr);
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break;
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case 32:
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write32(ptr);
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break;
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case 64:
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write64(ptr);
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break;
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default:
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VERIFY_NOT_REACHED();
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}
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}
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int main(int argc, char** argv)
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{
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bool do_static = false;
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int size = 10 * PAGE_SIZE;
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int offset = 10 * PAGE_SIZE - 1;
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int bits = 16;
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auto args_parser = Core::ArgsParser();
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args_parser.set_general_help(
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"Access out of bounds memory; a great testcase for UserEmulator.");
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args_parser.add_option(do_static, "Use a static region instead of an mmap'ed region. Fixes 'size' to 10*PAGESIZE = 40960. (Default: false)", "static", 'S');
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args_parser.add_option(size, "The size of the region to allocate. (Default: 10*PAGESIZE = 40960)", "size", 's', "size");
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args_parser.add_option(offset, "The signed offset at which to start writing. (Default: 10*PAGESIZE-1 = 40959)", "offset", 'o', "offset");
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args_parser.add_option(bits, "Amount of bits to write in a single instruction. (Default: 16)", "bits", 'b', "bits");
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args_parser.parse(argc, argv);
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if (do_static)
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size = 10 * PAGE_SIZE;
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printf("Writing %d bits to %s region of size %d at offset %d.\n",
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bits, do_static ? "static" : "MMAP", size, offset);
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if (do_static) {
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// Let's just hope the linker puts nothing after it!
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static unsigned char region[PAGE_SIZE * 10] = { 0 };
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run_test(region, offset, 64);
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} else {
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void* region = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
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VERIFY(region);
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run_test(region, offset, bits);
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}
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printf("FAIL (should have caused SIGSEGV)\n");
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return 1;
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}
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