1 //===-- enable_execute_stack_test.c - Test __enable_execute_stack ----------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 11 #include <stdio.h> 12 #include <string.h> 13 #include <stdint.h> 14 #if defined(_WIN32) 15 #include <windows.h> 16 void __clear_cache(void* start, void* end) 17 { 18 if (!FlushInstructionCache(GetCurrentProcess(), start, end-start)) 19 exit(1); 20 } 21 void __enable_execute_stack(void *addr) 22 { 23 MEMORY_BASIC_INFORMATION b; 24 25 if (!VirtualQuery(addr, &b, sizeof(b))) 26 exit(1); 27 if (!VirtualProtect(b.BaseAddress, b.RegionSize, PAGE_EXECUTE_READWRITE, &b.Protect)) 28 exit(1); 29 } 30 #else 31 #include <sys/mman.h> 32 extern void __clear_cache(void* start, void* end); 33 extern void __enable_execute_stack(void* addr); 34 #endif 35 36 typedef int (*pfunc)(void); 37 38 int func1() 39 { 40 return 1; 41 } 42 43 int func2() 44 { 45 return 2; 46 } 47 48 void *__attribute__((noinline)) 49 memcpy_f(void *dst, const void *src, size_t n) { 50 // ARM and MIPS nartually align functions, but use the LSB for ISA selection 51 // (THUMB, MIPS16/uMIPS respectively). Ensure that the ISA bit is ignored in 52 // the memcpy 53 #if defined(__arm__) || defined(__mips__) 54 return (void *)((uintptr_t)memcpy(dst, (void *)((uintptr_t)src & ~1), n) | 55 ((uintptr_t)src & 1)); 56 #else 57 return memcpy(dst, (void *)((uintptr_t)src), n); 58 #endif 59 } 60 61 int main() 62 { 63 unsigned char execution_buffer[128]; 64 // mark stack page containing execution_buffer to be executable 65 __enable_execute_stack(execution_buffer); 66 67 // verify you can copy and execute a function 68 pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, 128); 69 __clear_cache(execution_buffer, &execution_buffer[128]); 70 if ((*f1)() != 1) 71 return 1; 72 73 // verify you can overwrite a function with another 74 pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, 128); 75 __clear_cache(execution_buffer, &execution_buffer[128]); 76 if ((*f2)() != 2) 77 return 1; 78 79 return 0; 80 } 81
