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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
00f496c4 KC |
2 | /* |
3 | * This is for all the tests related to logic bugs (e.g. bad dereferences, | |
4 | * bad alignment, bad loops, bad locking, bad scheduling, deep stacks, and | |
5 | * lockups) along with other things that don't fit well into existing LKDTM | |
6 | * test source files. | |
7 | */ | |
00f496c4 | 8 | #include "lkdtm.h" |
6819d101 | 9 | #include <linux/list.h> |
6d2e91a6 | 10 | #include <linux/sched.h> |
e22aa9d7 | 11 | #include <linux/sched/signal.h> |
7b25a85c | 12 | #include <linux/sched/task_stack.h> |
e22aa9d7 | 13 | #include <linux/uaccess.h> |
00f496c4 | 14 | |
6819d101 KC |
15 | struct lkdtm_list { |
16 | struct list_head node; | |
17 | }; | |
18 | ||
00f496c4 KC |
19 | /* |
20 | * Make sure our attempts to over run the kernel stack doesn't trigger | |
21 | * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we | |
22 | * recurse past the end of THREAD_SIZE by default. | |
23 | */ | |
24 | #if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0) | |
25 | #define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2) | |
26 | #else | |
27 | #define REC_STACK_SIZE (THREAD_SIZE / 8) | |
28 | #endif | |
29 | #define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2) | |
30 | ||
31 | static int recur_count = REC_NUM_DEFAULT; | |
32 | ||
33 | static DEFINE_SPINLOCK(lock_me_up); | |
34 | ||
35 | static int recursive_loop(int remaining) | |
36 | { | |
37 | char buf[REC_STACK_SIZE]; | |
38 | ||
39 | /* Make sure compiler does not optimize this away. */ | |
40 | memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE); | |
41 | if (!remaining) | |
42 | return 0; | |
43 | else | |
44 | return recursive_loop(remaining - 1); | |
45 | } | |
46 | ||
47 | /* If the depth is negative, use the default, otherwise keep parameter. */ | |
48 | void __init lkdtm_bugs_init(int *recur_param) | |
49 | { | |
50 | if (*recur_param < 0) | |
51 | *recur_param = recur_count; | |
52 | else | |
53 | recur_count = *recur_param; | |
54 | } | |
55 | ||
56 | void lkdtm_PANIC(void) | |
57 | { | |
58 | panic("dumptest"); | |
59 | } | |
60 | ||
61 | void lkdtm_BUG(void) | |
62 | { | |
63 | BUG(); | |
64 | } | |
65 | ||
d32f11ba KC |
66 | static int warn_counter; |
67 | ||
00f496c4 KC |
68 | void lkdtm_WARNING(void) |
69 | { | |
d32f11ba | 70 | WARN(1, "Warning message trigger count: %d\n", warn_counter++); |
00f496c4 KC |
71 | } |
72 | ||
73 | void lkdtm_EXCEPTION(void) | |
74 | { | |
9e18308a | 75 | *((volatile int *) 0) = 0; |
00f496c4 KC |
76 | } |
77 | ||
78 | void lkdtm_LOOP(void) | |
79 | { | |
80 | for (;;) | |
81 | ; | |
82 | } | |
83 | ||
84 | void lkdtm_OVERFLOW(void) | |
85 | { | |
86 | (void) recursive_loop(recur_count); | |
87 | } | |
88 | ||
7a11a1d1 AB |
89 | static noinline void __lkdtm_CORRUPT_STACK(void *stack) |
90 | { | |
93e78c6b | 91 | memset(stack, '\xff', 64); |
7a11a1d1 AB |
92 | } |
93 | ||
93e78c6b | 94 | /* This should trip the stack canary, not corrupt the return address. */ |
00f496c4 KC |
95 | noinline void lkdtm_CORRUPT_STACK(void) |
96 | { | |
97 | /* Use default char array length that triggers stack protection. */ | |
93e78c6b KC |
98 | char data[8] __aligned(sizeof(void *)); |
99 | ||
100 | __lkdtm_CORRUPT_STACK(&data); | |
101 | ||
102 | pr_info("Corrupted stack containing char array ...\n"); | |
103 | } | |
104 | ||
105 | /* Same as above but will only get a canary with -fstack-protector-strong */ | |
106 | noinline void lkdtm_CORRUPT_STACK_STRONG(void) | |
107 | { | |
108 | union { | |
109 | unsigned short shorts[4]; | |
110 | unsigned long *ptr; | |
111 | } data __aligned(sizeof(void *)); | |
112 | ||
7a11a1d1 | 113 | __lkdtm_CORRUPT_STACK(&data); |
00f496c4 | 114 | |
93e78c6b | 115 | pr_info("Corrupted stack containing union ...\n"); |
00f496c4 KC |
116 | } |
117 | ||
118 | void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void) | |
119 | { | |
120 | static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5}; | |
121 | u32 *p; | |
122 | u32 val = 0x12345678; | |
123 | ||
124 | p = (u32 *)(data + 1); | |
125 | if (*p == 0) | |
126 | val = 0x87654321; | |
127 | *p = val; | |
128 | } | |
129 | ||
130 | void lkdtm_SOFTLOCKUP(void) | |
131 | { | |
132 | preempt_disable(); | |
133 | for (;;) | |
134 | cpu_relax(); | |
135 | } | |
136 | ||
137 | void lkdtm_HARDLOCKUP(void) | |
138 | { | |
139 | local_irq_disable(); | |
140 | for (;;) | |
141 | cpu_relax(); | |
142 | } | |
143 | ||
144 | void lkdtm_SPINLOCKUP(void) | |
145 | { | |
146 | /* Must be called twice to trigger. */ | |
147 | spin_lock(&lock_me_up); | |
148 | /* Let sparse know we intended to exit holding the lock. */ | |
149 | __release(&lock_me_up); | |
150 | } | |
151 | ||
152 | void lkdtm_HUNG_TASK(void) | |
153 | { | |
154 | set_current_state(TASK_UNINTERRUPTIBLE); | |
155 | schedule(); | |
156 | } | |
157 | ||
6819d101 KC |
158 | void lkdtm_CORRUPT_LIST_ADD(void) |
159 | { | |
160 | /* | |
161 | * Initially, an empty list via LIST_HEAD: | |
162 | * test_head.next = &test_head | |
163 | * test_head.prev = &test_head | |
164 | */ | |
165 | LIST_HEAD(test_head); | |
166 | struct lkdtm_list good, bad; | |
167 | void *target[2] = { }; | |
168 | void *redirection = ⌖ | |
169 | ||
170 | pr_info("attempting good list addition\n"); | |
171 | ||
172 | /* | |
173 | * Adding to the list performs these actions: | |
174 | * test_head.next->prev = &good.node | |
175 | * good.node.next = test_head.next | |
176 | * good.node.prev = test_head | |
177 | * test_head.next = good.node | |
178 | */ | |
179 | list_add(&good.node, &test_head); | |
180 | ||
181 | pr_info("attempting corrupted list addition\n"); | |
182 | /* | |
183 | * In simulating this "write what where" primitive, the "what" is | |
184 | * the address of &bad.node, and the "where" is the address held | |
185 | * by "redirection". | |
186 | */ | |
187 | test_head.next = redirection; | |
188 | list_add(&bad.node, &test_head); | |
189 | ||
190 | if (target[0] == NULL && target[1] == NULL) | |
191 | pr_err("Overwrite did not happen, but no BUG?!\n"); | |
192 | else | |
193 | pr_err("list_add() corruption not detected!\n"); | |
194 | } | |
195 | ||
196 | void lkdtm_CORRUPT_LIST_DEL(void) | |
197 | { | |
198 | LIST_HEAD(test_head); | |
199 | struct lkdtm_list item; | |
200 | void *target[2] = { }; | |
201 | void *redirection = ⌖ | |
202 | ||
203 | list_add(&item.node, &test_head); | |
204 | ||
205 | pr_info("attempting good list removal\n"); | |
206 | list_del(&item.node); | |
207 | ||
208 | pr_info("attempting corrupted list removal\n"); | |
209 | list_add(&item.node, &test_head); | |
210 | ||
211 | /* As with the list_add() test above, this corrupts "next". */ | |
212 | item.node.next = redirection; | |
213 | list_del(&item.node); | |
214 | ||
215 | if (target[0] == NULL && target[1] == NULL) | |
216 | pr_err("Overwrite did not happen, but no BUG?!\n"); | |
217 | else | |
218 | pr_err("list_del() corruption not detected!\n"); | |
219 | } | |
e22aa9d7 | 220 | |
7b25a85c | 221 | /* Test if unbalanced set_fs(KERNEL_DS)/set_fs(USER_DS) check exists. */ |
e22aa9d7 KC |
222 | void lkdtm_CORRUPT_USER_DS(void) |
223 | { | |
224 | pr_info("setting bad task size limit\n"); | |
225 | set_fs(KERNEL_DS); | |
226 | ||
227 | /* Make sure we do not keep running with a KERNEL_DS! */ | |
228 | force_sig(SIGKILL, current); | |
229 | } | |
7b25a85c KC |
230 | |
231 | /* Test that VMAP_STACK is actually allocating with a leading guard page */ | |
232 | void lkdtm_STACK_GUARD_PAGE_LEADING(void) | |
233 | { | |
234 | const unsigned char *stack = task_stack_page(current); | |
235 | const unsigned char *ptr = stack - 1; | |
236 | volatile unsigned char byte; | |
237 | ||
238 | pr_info("attempting bad read from page below current stack\n"); | |
239 | ||
240 | byte = *ptr; | |
241 | ||
242 | pr_err("FAIL: accessed page before stack!\n"); | |
243 | } | |
244 | ||
245 | /* Test that VMAP_STACK is actually allocating with a trailing guard page */ | |
246 | void lkdtm_STACK_GUARD_PAGE_TRAILING(void) | |
247 | { | |
248 | const unsigned char *stack = task_stack_page(current); | |
249 | const unsigned char *ptr = stack + THREAD_SIZE; | |
250 | volatile unsigned char byte; | |
251 | ||
252 | pr_info("attempting bad read from page above current stack\n"); | |
253 | ||
254 | byte = *ptr; | |
255 | ||
256 | pr_err("FAIL: accessed page after stack!\n"); | |
257 | } |