203 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * Test that loads/stores expand the stack segment, or trigger a SEGV, in4 * various conditions.5 *6 * Based on test code by Tom Lane.7 */8 9#undef NDEBUG10#include <assert.h>11 12#include <err.h>13#include <errno.h>14#include <stdio.h>15#include <signal.h>16#include <stdlib.h>17#include <string.h>18#include <sys/resource.h>19#include <sys/time.h>20#include <sys/types.h>21#include <sys/wait.h>22#include <unistd.h>23 24#define _KB (1024)25#define _MB (1024 * 1024)26 27volatile char *stack_top_ptr;28volatile unsigned long stack_top_sp;29volatile char c;30 31enum access_type {32 LOAD,33 STORE,34};35 36/*37 * Consume stack until the stack pointer is below @target_sp, then do an access38 * (load or store) at offset @delta from either the base of the stack or the39 * current stack pointer.40 */41__attribute__ ((noinline))42int consume_stack(unsigned long target_sp, unsigned long stack_high, int delta, enum access_type type)43{44 unsigned long target;45 char stack_cur;46 47 if ((unsigned long)&stack_cur > target_sp)48 return consume_stack(target_sp, stack_high, delta, type);49 else {50 // We don't really need this, but without it GCC might not51 // generate a recursive call above.52 stack_top_ptr = &stack_cur;53 54#ifdef __powerpc__55 asm volatile ("mr %[sp], %%r1" : [sp] "=r" (stack_top_sp));56#else57 asm volatile ("mov %%rsp, %[sp]" : [sp] "=r" (stack_top_sp));58#endif59 target = stack_high - delta + 1;60 volatile char *p = (char *)target;61 62 if (type == STORE)63 *p = c;64 else65 c = *p;66 67 // Do something to prevent the stack frame being popped prior to68 // our access above.69 getpid();70 }71 72 return 0;73}74 75static int search_proc_maps(char *needle, unsigned long *low, unsigned long *high)76{77 unsigned long start, end;78 static char buf[4096];79 char name[128];80 FILE *f;81 int rc;82 83 f = fopen("/proc/self/maps", "r");84 if (!f) {85 perror("fopen");86 return -1;87 }88 89 while (fgets(buf, sizeof(buf), f)) {90 rc = sscanf(buf, "%lx-%lx %*c%*c%*c%*c %*x %*d:%*d %*d %127s\n",91 &start, &end, name);92 if (rc == 2)93 continue;94 95 if (rc != 3) {96 printf("sscanf errored\n");97 rc = -1;98 break;99 }100 101 if (strstr(name, needle)) {102 *low = start;103 *high = end - 1;104 rc = 0;105 break;106 }107 }108 109 fclose(f);110 111 return rc;112}113 114int child(unsigned int stack_used, int delta, enum access_type type)115{116 unsigned long low, stack_high;117 118 assert(search_proc_maps("[stack]", &low, &stack_high) == 0);119 120 assert(consume_stack(stack_high - stack_used, stack_high, delta, type) == 0);121 122 printf("Access OK: %s delta %-7d used size 0x%06x stack high 0x%lx top_ptr %p top sp 0x%lx actual used 0x%lx\n",123 type == LOAD ? "load" : "store", delta, stack_used, stack_high,124 stack_top_ptr, stack_top_sp, stack_high - stack_top_sp + 1);125 126 return 0;127}128 129static int test_one(unsigned int stack_used, int delta, enum access_type type)130{131 pid_t pid;132 int rc;133 134 pid = fork();135 if (pid == 0)136 exit(child(stack_used, delta, type));137 138 assert(waitpid(pid, &rc, 0) != -1);139 140 if (WIFEXITED(rc) && WEXITSTATUS(rc) == 0)141 return 0;142 143 // We don't expect a non-zero exit that's not a signal144 assert(!WIFEXITED(rc));145 146 printf("Faulted: %s delta %-7d used size 0x%06x signal %d\n",147 type == LOAD ? "load" : "store", delta, stack_used,148 WTERMSIG(rc));149 150 return 1;151}152 153// This is fairly arbitrary but is well below any of the targets below,154// so that the delta between the stack pointer and the target is large.155#define DEFAULT_SIZE (32 * _KB)156 157static void test_one_type(enum access_type type, unsigned long page_size, unsigned long rlim_cur)158{159 unsigned long delta;160 161 // We should be able to access anywhere within the rlimit162 for (delta = page_size; delta <= rlim_cur; delta += page_size)163 assert(test_one(DEFAULT_SIZE, delta, type) == 0);164 165 assert(test_one(DEFAULT_SIZE, rlim_cur, type) == 0);166 167 // But if we go past the rlimit it should fail168 assert(test_one(DEFAULT_SIZE, rlim_cur + 1, type) != 0);169}170 171static int test(void)172{173 unsigned long page_size;174 struct rlimit rlimit;175 176 page_size = getpagesize();177 getrlimit(RLIMIT_STACK, &rlimit);178 printf("Stack rlimit is 0x%lx\n", rlimit.rlim_cur);179 180 printf("Testing loads ...\n");181 test_one_type(LOAD, page_size, rlimit.rlim_cur);182 printf("Testing stores ...\n");183 test_one_type(STORE, page_size, rlimit.rlim_cur);184 185 printf("All OK\n");186 187 return 0;188}189 190#ifdef __powerpc__191#include "utils.h"192 193int main(void)194{195 return test_harness(test, "stack_expansion_ldst");196}197#else198int main(void)199{200 return test();201}202#endif203