From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions When using eBPF to probe CS CALL instructions within a function, a crash can be triggered. The eBPF tool probes offset 257 of the __hrtimer_run_queues() function: <__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1) <__hrtimer_run_queues+254>: mov %r14,%rdi <__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12> <__hrtimer_run_queues+263>: mov %eax,%r12d <__hrtimer_run_queues+266>: xchg %ax,%ax <__hrtimer_run_queues+268>: mov %r13,%rdi Which triggers this crash: BUG: unable to handle page fault for address: 00000000000f41c9 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P RIP: 0010:__hrtimer_run_queues+0x106/0x230 Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is at the 6th byte of the above CS CALL instruction. Since the CS CALL instruction occupies 6 bytes, the exception occurred in the middle of that call instruction. The root cause is that when using eBPF tools to probe in the middle of a function, a kprobe with INT3 is used as the underlying implementation. During single-step emulation of the original CALL instruction, int3_emulate_call() assumes that the probed CALL instruction is 5 bytes long. However, the actual CS-prefixed CALL instruction occupies 6 bytes, so it constructs an incorrect exception return address. When the CPU returns from the kprobe handler, the next instruction to be executed is at the address of the last byte of that CS CALL instruction. Coincidentally, starting from that address, the CPU fetches and decodes a completely different instruction, which ultimately triggers a kernel crash. Fix the issue by using the actual instruction length obtained from the instruction decoder when constructing the exception return address, rather than relying on the hardcoded CALL_INSN_SIZE macro. [ mingo: Refined the changelog ] Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step") Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- lib/kunit/executor.c | 442 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 442 insertions(+) create mode 100644 lib/kunit/executor.c (limited to 'lib/kunit/executor.c') diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c new file mode 100644 index 000000000..b0f8a41d6 --- /dev/null +++ b/lib/kunit/executor.c @@ -0,0 +1,442 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include + +/* + * These symbols point to the .kunit_test_suites section and are defined in + * include/asm-generic/vmlinux.lds.h, and consequently must be extern. + */ +extern struct kunit_suite * const __kunit_suites_start[]; +extern struct kunit_suite * const __kunit_suites_end[]; +extern struct kunit_suite * const __kunit_init_suites_start[]; +extern struct kunit_suite * const __kunit_init_suites_end[]; + +static struct kunit_suite_set kunit_boot_suites; + +void kunit_free_boot_suites(void) +{ + if (kunit_boot_suites.start) { + kunit_free_suite_set(kunit_boot_suites); + kunit_boot_suites = (struct kunit_suite_set){ NULL, NULL }; + } +} + +static char *action_param; + +module_param_named(action, action_param, charp, 0400); +MODULE_PARM_DESC(action, + "Changes KUnit executor behavior, valid values are:\n" + ": run the tests like normal\n" + "'list' to list test names instead of running them.\n" + "'list_attr' to list test names and attributes instead of running them.\n"); + +const char *kunit_action(void) +{ + return action_param; +} + +/* + * Run KUnit tests after initialization + */ +#ifdef CONFIG_KUNIT_AUTORUN_ENABLED +static bool autorun_param = true; +#else +static bool autorun_param; +#endif +module_param_named(autorun, autorun_param, bool, 0); +MODULE_PARM_DESC(autorun, "Run KUnit tests after initialization"); + +bool kunit_autorun(void) +{ + return autorun_param; +} + +#define PARAM_FROM_CONFIG(config) (config[0] ? config : NULL) + +static char *filter_glob_param = PARAM_FROM_CONFIG(CONFIG_KUNIT_DEFAULT_FILTER_GLOB); +static char *filter_param = PARAM_FROM_CONFIG(CONFIG_KUNIT_DEFAULT_FILTER); +static char *filter_action_param = PARAM_FROM_CONFIG(CONFIG_KUNIT_DEFAULT_FILTER_ACTION); + +module_param_named(filter_glob, filter_glob_param, charp, 0600); +MODULE_PARM_DESC(filter_glob, + "Filter which KUnit test suites/tests run at boot-time, e.g. list* or list*.*del_test"); +module_param_named(filter, filter_param, charp, 0600); +MODULE_PARM_DESC(filter, + "Filter which KUnit test suites/tests run at boot-time using attributes, e.g. speed>slow"); +module_param_named(filter_action, filter_action_param, charp, 0600); +MODULE_PARM_DESC(filter_action, + "Changes behavior of filtered tests using attributes, valid values are:\n" + ": do not run filtered tests as normal\n" + "'skip': skip all filtered tests instead so tests will appear in output\n"); + +const char *kunit_filter_glob(void) +{ + return filter_glob_param; +} + +char *kunit_filter(void) +{ + return filter_param; +} + +char *kunit_filter_action(void) +{ + return filter_action_param; +} + +/* glob_match() needs NULL terminated strings, so we need a copy of filter_glob_param. */ +struct kunit_glob_filter { + char *suite_glob; + char *test_glob; +}; + +/* Split "suite_glob.test_glob" into two. Assumes filter_glob is not empty. */ +static int kunit_parse_glob_filter(struct kunit_glob_filter *parsed, + const char *filter_glob) +{ + const char *period = strchr(filter_glob, '.'); + + if (!period) { + parsed->suite_glob = kstrdup(filter_glob, GFP_KERNEL); + if (!parsed->suite_glob) + return -ENOMEM; + parsed->test_glob = NULL; + return 0; + } + + parsed->suite_glob = kstrndup(filter_glob, period - filter_glob, GFP_KERNEL); + if (!parsed->suite_glob) + return -ENOMEM; + + parsed->test_glob = kstrdup(period + 1, GFP_KERNEL); + if (!parsed->test_glob) { + kfree(parsed->suite_glob); + return -ENOMEM; + } + + return 0; +} + +/* Create a copy of suite with only tests that match test_glob. */ +static struct kunit_suite * +kunit_filter_glob_tests(const struct kunit_suite *const suite, const char *test_glob) +{ + int n = 0; + struct kunit_case *filtered, *test_case; + struct kunit_suite *copy; + + kunit_suite_for_each_test_case(suite, test_case) { + if (!test_glob || glob_match(test_glob, test_case->name)) + ++n; + } + + if (n == 0) + return NULL; + + copy = kmemdup(suite, sizeof(*copy), GFP_KERNEL); + if (!copy) + return ERR_PTR(-ENOMEM); + + filtered = kzalloc_objs(*filtered, n + 1); + if (!filtered) { + kfree(copy); + return ERR_PTR(-ENOMEM); + } + + n = 0; + kunit_suite_for_each_test_case(suite, test_case) { + if (!test_glob || glob_match(test_glob, test_case->name)) + filtered[n++] = *test_case; + } + + copy->test_cases = filtered; + return copy; +} + +void kunit_free_suite_set(struct kunit_suite_set suite_set) +{ + struct kunit_suite * const *suites; + + for (suites = suite_set.start; suites < suite_set.end; suites++) { + kfree((*suites)->test_cases); + kfree(*suites); + } + kfree(suite_set.start); +} + +/* + * Filter and reallocate test suites. Must return the filtered test suites set + * allocated at a valid virtual address or NULL in case of error. + */ +struct kunit_suite_set +kunit_filter_suites(const struct kunit_suite_set *suite_set, + const char *filter_glob, + char *filters, + char *filter_action, + int *err) +{ + int i, j, k; + int filter_count = 0; + struct kunit_suite **copy, **copy_start, *filtered_suite, *new_filtered_suite; + struct kunit_suite_set filtered = {NULL, NULL}; + struct kunit_glob_filter parsed_glob; + struct kunit_attr_filter *parsed_filters = NULL; + struct kunit_suite * const *suites; + + const size_t max = suite_set->end - suite_set->start; + + copy = kzalloc_objs(*copy, max); + if (!copy) { /* won't be able to run anything, return an empty set */ + return filtered; + } + copy_start = copy; + + if (filter_glob) { + *err = kunit_parse_glob_filter(&parsed_glob, filter_glob); + if (*err) + goto free_copy; + } + + /* Parse attribute filters */ + if (filters) { + filter_count = kunit_get_filter_count(filters); + parsed_filters = kzalloc_objs(*parsed_filters, filter_count); + if (!parsed_filters) { + *err = -ENOMEM; + goto free_parsed_glob; + } + for (j = 0; j < filter_count; j++) + parsed_filters[j] = kunit_next_attr_filter(&filters, err); + if (*err) + goto free_parsed_filters; + } + + for (i = 0; &suite_set->start[i] != suite_set->end; i++) { + filtered_suite = suite_set->start[i]; + if (filter_glob) { + if (!glob_match(parsed_glob.suite_glob, filtered_suite->name)) + continue; + filtered_suite = kunit_filter_glob_tests(filtered_suite, + parsed_glob.test_glob); + if (IS_ERR(filtered_suite)) { + *err = PTR_ERR(filtered_suite); + goto free_filtered_suite; + } + } + if (filter_count > 0 && parsed_filters != NULL) { + for (k = 0; k < filter_count; k++) { + new_filtered_suite = kunit_filter_attr_tests(filtered_suite, + parsed_filters[k], filter_action, err); + + /* Free previous copy of suite */ + if (k > 0 || filter_glob) { + kfree(filtered_suite->test_cases); + kfree(filtered_suite); + } + + filtered_suite = new_filtered_suite; + + if (*err) + goto free_filtered_suite; + + if (IS_ERR(filtered_suite)) { + *err = PTR_ERR(filtered_suite); + goto free_filtered_suite; + } + if (!filtered_suite) + break; + } + } + + if (!filtered_suite) + continue; + + *copy++ = filtered_suite; + } + filtered.start = copy_start; + filtered.end = copy; + +free_filtered_suite: + if (*err) { + for (suites = copy_start; suites < copy; suites++) { + kfree((*suites)->test_cases); + kfree(*suites); + } + } + +free_parsed_filters: + if (filter_count) + kfree(parsed_filters); + +free_parsed_glob: + if (filter_glob) { + kfree(parsed_glob.suite_glob); + kfree(parsed_glob.test_glob); + } + +free_copy: + if (*err) + kfree(copy_start); + + return filtered; +} + +void kunit_exec_run_tests(struct kunit_suite_set *suite_set, bool builtin) +{ + size_t num_suites = suite_set->end - suite_set->start; + bool autorun = kunit_autorun(); + + if (autorun && (builtin || num_suites)) { + pr_info("KTAP version 1\n"); + pr_info("1..%zu\n", num_suites); + } + + __kunit_test_suites_init(suite_set->start, num_suites, autorun); +} + +void kunit_exec_list_tests(struct kunit_suite_set *suite_set, bool include_attr) +{ + struct kunit_suite * const *suites; + struct kunit_case *test_case; + + /* Hack: print a ktap header so kunit.py can find the start of KUnit output. */ + pr_info("KTAP version 1\n"); + + for (suites = suite_set->start; suites < suite_set->end; suites++) { + /* Print suite name and suite attributes */ + pr_info("%s\n", (*suites)->name); + if (include_attr) + kunit_print_attr((void *)(*suites), false, 0); + + /* Print test case name and attributes in suite */ + kunit_suite_for_each_test_case((*suites), test_case) { + pr_info("%s.%s\n", (*suites)->name, test_case->name); + if (include_attr) + kunit_print_attr((void *)test_case, true, 0); + } + } +} + +struct kunit_suite_set kunit_merge_suite_sets(struct kunit_suite_set init_suite_set, + struct kunit_suite_set suite_set) +{ + struct kunit_suite_set total_suite_set = {NULL, NULL}; + struct kunit_suite **total_suite_start = NULL; + size_t init_num_suites, num_suites, suite_size; + int i = 0; + + init_num_suites = init_suite_set.end - init_suite_set.start; + num_suites = suite_set.end - suite_set.start; + suite_size = sizeof(suite_set.start); + + /* Allocate memory for array of all kunit suites */ + total_suite_start = kmalloc_array(init_num_suites + num_suites, suite_size, GFP_KERNEL); + if (!total_suite_start) + return total_suite_set; + + /* Append and mark init suites and then append all other kunit suites */ + memcpy(total_suite_start, init_suite_set.start, init_num_suites * suite_size); + for (i = 0; i < init_num_suites; i++) + total_suite_start[i]->is_init = true; + + memcpy(total_suite_start + init_num_suites, suite_set.start, num_suites * suite_size); + + /* Set kunit suite set start and end */ + total_suite_set.start = total_suite_start; + total_suite_set.end = total_suite_start + (init_num_suites + num_suites); + + return total_suite_set; +} + +#if IS_BUILTIN(CONFIG_KUNIT) + +static char *kunit_shutdown; +core_param(kunit_shutdown, kunit_shutdown, charp, 0644); + +static void kunit_handle_shutdown(void) +{ + if (!kunit_shutdown) + return; + + if (!strcmp(kunit_shutdown, "poweroff")) + kernel_power_off(); + else if (!strcmp(kunit_shutdown, "halt")) + kernel_halt(); + else if (!strcmp(kunit_shutdown, "reboot")) + kernel_restart(NULL); + +} + +int kunit_run_all_tests(void) +{ + struct kunit_suite_set suite_set = {NULL, NULL}; + struct kunit_suite_set filtered_suite_set = {NULL, NULL}; + struct kunit_suite_set init_suite_set = { + __kunit_init_suites_start, __kunit_init_suites_end, + }; + struct kunit_suite_set normal_suite_set = { + __kunit_suites_start, __kunit_suites_end, + }; + size_t init_num_suites = init_suite_set.end - init_suite_set.start; + int err = 0; + + if (init_num_suites > 0) { + suite_set = kunit_merge_suite_sets(init_suite_set, normal_suite_set); + if (!suite_set.start) + goto out; + } else + suite_set = normal_suite_set; + + if (!kunit_enabled()) { + pr_info("kunit: disabled\n"); + goto free_out; + } + + if (filter_glob_param || filter_param) { + filtered_suite_set = kunit_filter_suites(&suite_set, filter_glob_param, + filter_param, filter_action_param, &err); + + /* Free original suite set before using filtered suite set */ + if (init_num_suites > 0) + kfree(suite_set.start); + suite_set = filtered_suite_set; + + if (err) { + pr_err("kunit executor: error filtering suites: %d\n", err); + goto free_out; + } + } + + if (!action_param) + kunit_exec_run_tests(&suite_set, true); + else if (strcmp(action_param, "list") == 0) + kunit_exec_list_tests(&suite_set, false); + else if (strcmp(action_param, "list_attr") == 0) + kunit_exec_list_tests(&suite_set, true); + else + pr_err("kunit executor: unknown action '%s'\n", action_param); + +free_out: + if (filter_glob_param || filter_param) { + if (err) + kunit_free_suite_set(suite_set); + else + kunit_boot_suites = suite_set; + } else if (init_num_suites > 0) + /* Don't use kunit_free_suite_set because suites aren't individually allocated */ + kfree(suite_set.start); + +out: + kunit_handle_shutdown(); + return err; +} + +#if IS_BUILTIN(CONFIG_KUNIT_TEST) +#include "executor_test.c" +#endif + +#endif /* IS_BUILTIN(CONFIG_KUNIT) */ -- cgit v1.3.1