test_kprobes: clear kprobes between test runs

Running the kprobes sanity tests twice makes all tests fail and eventually crashes the kernel. [root@martin-riscv-1 ~]# echo 1 > /sys/kernel/debug/kunit/kprobes_test/run ... # Totals: pass:5 fail:0 skip:0 total:5 ok 1 kprobes_test [root@martin-riscv-1 ~]# echo 1 > /sys/kernel/debug/kunit/kprobes_test/run ... # test_kprobe: EXPECTATION FAILED at lib/tests/test_kprobes.c:64 Expected 0 == register_kprobe(&kp), but register_kprobe(&kp) == -22 (0xffffffffffffffea) ... Unable to handle kernel paging request ... The testsuite defines several kprobes and kretprobes as static variables that are preserved across test runs. After register_kprobe and unregister_kprobe, a kprobe contains some leftover data that must be cleared before the kprobe can be registered again. The tests are setting symbol_name to define the probe location. Address and flags must be cleared. The existing code clears some of the probes between subsequent tests, but not between two test runs. The leftover data from a previous test run makes the registrations fail in the next run. Move the cleanups for all kprobes into kprobes_test_init, this function is called before each single test (including the first test of a test run). Link: https://lore.kernel.org/all/20260507134615.1010905-1-martin@kaiser.cx/

Martin Kaiser committed 6 months ago

Commit ef5581b1 parent 307abfa1 file · +18 −11Browse files

Unified · Split

lib/tests/test_kprobes.c+18−11

@@ -12,6 +12,12 @@ · 11 unmodified lines
12	12
13	13	#define div_factor 3
14	14
	15	+#define KP_CLEAR(_kp) \
	16	+do { \
	17	+ (_kp).addr = NULL; \
	18	+ (_kp).flags = 0; \
	19	+} while (0)
	20	+
15	21	static u32 rand1, preh_val, posth_val;
16	22	static u32 (*target)(u32 value);
17	23	static u32 (*recursed_target)(u32 value);
@@ -125,10 +131,6 @@ static void test_kprobes(struct kunit *test) · 107 unmodified lines
125	131
126	132	current_test = test;
127	133
128		− /* addr and flags should be cleard for reusing kprobe. */
129		− kp.addr = NULL;
130		− kp.flags = 0;
131		−
132	134	KUNIT_EXPECT_EQ(test, 0, register_kprobes(kps, 2));
133	135	preh_val = 0;
134	136	posth_val = 0;
@@ -226,9 +228,6 @@ static void test_kretprobes(struct kunit *test) · 91 unmodified lines
226	228	struct kretprobe *rps[2] = {&rp, &rp2};
227	229
228	230	current_test = test;
229		− /* addr and flags should be cleard for reusing kprobe. */
230		− rp.kp.addr = NULL;
231		− rp.kp.flags = 0;
232	231	KUNIT_EXPECT_EQ(test, 0, register_kretprobes(rps, 2));
233	232
234	233	krph_val = 0;
@@ -290,8 +289,6 @@ static void test_stacktrace_on_kretprobe(struct kunit *test) · 55 unmodified lines
290	289	unsigned long myretaddr = (unsigned long)__builtin_return_address(0);
291	290
292	291	current_test = test;
293		− rp3.kp.addr = NULL;
294		− rp3.kp.flags = 0;
295	292
296	293	/*
297	294	* Run the stacktrace_driver() to record correct return address in
@@ -352,8 +349,6 @@ static void test_stacktrace_on_nested_kretprobe(struct kunit *test) · 54 unmodified lines
352	349	struct kretprobe *rps[2] = {&rp3, &rp4};
353	350
354	351	current_test = test;
355		− rp3.kp.addr = NULL;
356		− rp3.kp.flags = 0;
357	352
358	353	//KUNIT_ASSERT_NE(test, myretaddr, stacktrace_driver());
359	354
@@ -367,6 +362,18 @@ static void test_stacktrace_on_nested_kretprobe(struct kunit *test) · 7 unmodified lines
367	362
368	363	static int kprobes_test_init(struct kunit *test)
369	364	{
	365	+ KP_CLEAR(kp);
	366	+ KP_CLEAR(kp2);
	367	+ KP_CLEAR(kp_missed);
	368	+#ifdef CONFIG_KRETPROBES
	369	+ KP_CLEAR(rp.kp);
	370	+ KP_CLEAR(rp2.kp);
	371	+#ifdef CONFIG_ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
	372	+ KP_CLEAR(rp3.kp);
	373	+ KP_CLEAR(rp4.kp);
	374	+#endif
	375	+#endif
	376	+
370	377	target = kprobe_target;
371	378	target2 = kprobe_target2;
372	379	recursed_target = kprobe_recursed_target;