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10#define _GNU_SOURCE
11#include <signal.h>
12#include <stdio.h>
13#include <stdlib.h>
14#include <sys/mman.h>
15#include <ucontext.h>
16#include <alloca.h>
17#include <string.h>
18#include <assert.h>
19#include <errno.h>
20
21#include "../kselftest.h"
22
23#ifndef SS_AUTODISARM
24#define SS_AUTODISARM (1U << 31)
25#endif
26
27static void *sstack, *ustack;
28static ucontext_t uc, sc;
29static const char *msg = "[OK]\tStack preserved";
30static const char *msg2 = "[FAIL]\tStack corrupted";
31struct stk_data {
32 char msg[128];
33 int flag;
34};
35
36void my_usr1(int sig, siginfo_t *si, void *u)
37{
38 char *aa;
39 int err;
40 stack_t stk;
41 struct stk_data *p;
42
43#if __s390x__
44 register unsigned long sp asm("%15");
45#else
46 register unsigned long sp asm("sp");
47#endif
48
49 if (sp < (unsigned long)sstack ||
50 sp >= (unsigned long)sstack + SIGSTKSZ) {
51 ksft_exit_fail_msg("SP is not on sigaltstack\n");
52 }
53
54 aa = alloca(1024);
55 assert(aa);
56 p = (struct stk_data *)(aa + 512);
57 strcpy(p->msg, msg);
58 p->flag = 1;
59 ksft_print_msg("[RUN]\tsignal USR1\n");
60 err = sigaltstack(NULL, &stk);
61 if (err) {
62 ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
63 exit(EXIT_FAILURE);
64 }
65 if (stk.ss_flags != SS_DISABLE)
66 ksft_test_result_fail("tss_flags=%x, should be SS_DISABLE\n",
67 stk.ss_flags);
68 else
69 ksft_test_result_pass(
70 "sigaltstack is disabled in sighandler\n");
71 swapcontext(&sc, &uc);
72 ksft_print_msg("%s\n", p->msg);
73 if (!p->flag) {
74 ksft_exit_skip("[RUN]\tAborting\n");
75 exit(EXIT_FAILURE);
76 }
77}
78
79void my_usr2(int sig, siginfo_t *si, void *u)
80{
81 char *aa;
82 struct stk_data *p;
83
84 ksft_print_msg("[RUN]\tsignal USR2\n");
85 aa = alloca(1024);
86
87
88 p = memmem(aa, 1024, msg, strlen(msg));
89 if (p) {
90 ksft_test_result_fail("sigaltstack re-used\n");
91
92 strcpy(p->msg, msg2);
93
94 p->flag = 0;
95 }
96}
97
98static void switch_fn(void)
99{
100 ksft_print_msg("[RUN]\tswitched to user ctx\n");
101 raise(SIGUSR2);
102 setcontext(&sc);
103}
104
105int main(void)
106{
107 struct sigaction act;
108 stack_t stk;
109 int err;
110
111 ksft_print_header();
112
113 sigemptyset(&act.sa_mask);
114 act.sa_flags = SA_ONSTACK | SA_SIGINFO;
115 act.sa_sigaction = my_usr1;
116 sigaction(SIGUSR1, &act, NULL);
117 act.sa_sigaction = my_usr2;
118 sigaction(SIGUSR2, &act, NULL);
119 sstack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
120 MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
121 if (sstack == MAP_FAILED) {
122 ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
123 return EXIT_FAILURE;
124 }
125
126 err = sigaltstack(NULL, &stk);
127 if (err) {
128 ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
129 exit(EXIT_FAILURE);
130 }
131 if (stk.ss_flags == SS_DISABLE) {
132 ksft_test_result_pass(
133 "Initial sigaltstack state was SS_DISABLE\n");
134 } else {
135 ksft_exit_fail_msg("Initial sigaltstack state was %x; "
136 "should have been SS_DISABLE\n", stk.ss_flags);
137 return EXIT_FAILURE;
138 }
139
140 stk.ss_sp = sstack;
141 stk.ss_size = SIGSTKSZ;
142 stk.ss_flags = SS_ONSTACK | SS_AUTODISARM;
143 err = sigaltstack(&stk, NULL);
144 if (err) {
145 if (errno == EINVAL) {
146 ksft_exit_skip(
147 "[NOTE]\tThe running kernel doesn't support SS_AUTODISARM\n");
148
149
150
151
152
153
154 return 0;
155 } else {
156 ksft_exit_fail_msg(
157 "sigaltstack(SS_ONSTACK | SS_AUTODISARM) %s\n",
158 strerror(errno));
159 return EXIT_FAILURE;
160 }
161 }
162
163 ustack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
164 MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
165 if (ustack == MAP_FAILED) {
166 ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
167 return EXIT_FAILURE;
168 }
169 getcontext(&uc);
170 uc.uc_link = NULL;
171 uc.uc_stack.ss_sp = ustack;
172 uc.uc_stack.ss_size = SIGSTKSZ;
173 makecontext(&uc, switch_fn, 0);
174 raise(SIGUSR1);
175
176 err = sigaltstack(NULL, &stk);
177 if (err) {
178 ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
179 exit(EXIT_FAILURE);
180 }
181 if (stk.ss_flags != SS_AUTODISARM) {
182 ksft_exit_fail_msg("ss_flags=%x, should be SS_AUTODISARM\n",
183 stk.ss_flags);
184 exit(EXIT_FAILURE);
185 }
186 ksft_test_result_pass(
187 "sigaltstack is still SS_AUTODISARM after signal\n");
188
189 ksft_exit_pass();
190 return 0;
191}
192