| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * This file contains common KASAN error reporting code. |
| * |
| * Copyright (c) 2014 Samsung Electronics Co., Ltd. |
| * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> |
| * |
| * Some code borrowed from https://github.com/xairy/kasan-prototype by |
| * Andrey Konovalov <andreyknvl@gmail.com> |
| */ |
| |
| #include <linux/bitops.h> |
| #include <linux/ftrace.h> |
| #include <linux/init.h> |
| #include <linux/kernel.h> |
| #include <linux/mm.h> |
| #include <linux/printk.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <linux/stackdepot.h> |
| #include <linux/stacktrace.h> |
| #include <linux/string.h> |
| #include <linux/types.h> |
| #include <linux/kasan.h> |
| #include <linux/module.h> |
| #include <linux/sched/task_stack.h> |
| #include <linux/uaccess.h> |
| #include <trace/events/error_report.h> |
| |
| #include <asm/sections.h> |
| |
| #include <kunit/test.h> |
| |
| #include "kasan.h" |
| #include "../slab.h" |
| |
| static unsigned long kasan_flags; |
| |
| #define KASAN_BIT_REPORTED 0 |
| #define KASAN_BIT_MULTI_SHOT 1 |
| |
| enum kasan_arg_fault { |
| KASAN_ARG_FAULT_DEFAULT, |
| KASAN_ARG_FAULT_REPORT, |
| KASAN_ARG_FAULT_PANIC, |
| }; |
| |
| static enum kasan_arg_fault kasan_arg_fault __ro_after_init = KASAN_ARG_FAULT_DEFAULT; |
| |
| /* kasan.fault=report/panic */ |
| static int __init early_kasan_fault(char *arg) |
| { |
| if (!arg) |
| return -EINVAL; |
| |
| if (!strcmp(arg, "report")) |
| kasan_arg_fault = KASAN_ARG_FAULT_REPORT; |
| else if (!strcmp(arg, "panic")) |
| kasan_arg_fault = KASAN_ARG_FAULT_PANIC; |
| else |
| return -EINVAL; |
| |
| return 0; |
| } |
| early_param("kasan.fault", early_kasan_fault); |
| |
| bool kasan_save_enable_multi_shot(void) |
| { |
| return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); |
| } |
| EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot); |
| |
| void kasan_restore_multi_shot(bool enabled) |
| { |
| if (!enabled) |
| clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); |
| } |
| EXPORT_SYMBOL_GPL(kasan_restore_multi_shot); |
| |
| static int __init kasan_set_multi_shot(char *str) |
| { |
| set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); |
| return 1; |
| } |
| __setup("kasan_multi_shot", kasan_set_multi_shot); |
| |
| static void print_error_description(struct kasan_access_info *info) |
| { |
| pr_err("BUG: KASAN: %s in %pS\n", |
| kasan_get_bug_type(info), (void *)info->ip); |
| if (info->access_size) |
| pr_err("%s of size %zu at addr %px by task %s/%d\n", |
| info->is_write ? "Write" : "Read", info->access_size, |
| info->access_addr, current->comm, task_pid_nr(current)); |
| else |
| pr_err("%s at addr %px by task %s/%d\n", |
| info->is_write ? "Write" : "Read", |
| info->access_addr, current->comm, task_pid_nr(current)); |
| } |
| |
| static DEFINE_SPINLOCK(report_lock); |
| |
| static void start_report(unsigned long *flags) |
| { |
| /* |
| * Make sure we don't end up in loop. |
| */ |
| kasan_disable_current(); |
| spin_lock_irqsave(&report_lock, *flags); |
| pr_err("==================================================================\n"); |
| } |
| |
| static void end_report(unsigned long *flags, unsigned long addr) |
| { |
| if (!kasan_async_fault_possible()) |
| trace_error_report_end(ERROR_DETECTOR_KASAN, addr); |
| pr_err("==================================================================\n"); |
| add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); |
| spin_unlock_irqrestore(&report_lock, *flags); |
| if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) |
| check_panic_on_warn("KASAN"); |
| if (kasan_arg_fault == KASAN_ARG_FAULT_PANIC) |
| panic("kasan.fault=panic set ...\n"); |
| kasan_enable_current(); |
| } |
| |
| static void print_stack(depot_stack_handle_t stack) |
| { |
| unsigned long *entries; |
| unsigned int nr_entries; |
| |
| nr_entries = stack_depot_fetch(stack, &entries); |
| stack_trace_print(entries, nr_entries, 0); |
| } |
| |
| static void print_track(struct kasan_track *track, const char *prefix) |
| { |
| pr_err("%s by task %u:\n", prefix, track->pid); |
| if (track->stack) { |
| print_stack(track->stack); |
| } else { |
| pr_err("(stack is not available)\n"); |
| } |
| } |
| |
| struct page *kasan_addr_to_page(const void *addr) |
| { |
| if ((addr >= (void *)PAGE_OFFSET) && |
| (addr < high_memory)) |
| return virt_to_head_page(addr); |
| return NULL; |
| } |
| |
| static void describe_object_addr(struct kmem_cache *cache, void *object, |
| const void *addr) |
| { |
| unsigned long access_addr = (unsigned long)addr; |
| unsigned long object_addr = (unsigned long)object; |
| const char *rel_type; |
| int rel_bytes; |
| |
| pr_err("The buggy address belongs to the object at %px\n" |
| " which belongs to the cache %s of size %d\n", |
| object, cache->name, cache->object_size); |
| |
| if (!addr) |
| return; |
| |
| if (access_addr < object_addr) { |
| rel_type = "to the left"; |
| rel_bytes = object_addr - access_addr; |
| } else if (access_addr >= object_addr + cache->object_size) { |
| rel_type = "to the right"; |
| rel_bytes = access_addr - (object_addr + cache->object_size); |
| } else { |
| rel_type = "inside"; |
| rel_bytes = access_addr - object_addr; |
| } |
| |
| pr_err("The buggy address is located %d bytes %s of\n" |
| " %d-byte region [%px, %px)\n", |
| rel_bytes, rel_type, cache->object_size, (void *)object_addr, |
| (void *)(object_addr + cache->object_size)); |
| } |
| |
| static void describe_object_stacks(struct kmem_cache *cache, void *object, |
| const void *addr, u8 tag) |
| { |
| struct kasan_alloc_meta *alloc_meta; |
| struct kasan_track *free_track; |
| |
| alloc_meta = kasan_get_alloc_meta(cache, object); |
| if (alloc_meta) { |
| print_track(&alloc_meta->alloc_track, "Allocated"); |
| pr_err("\n"); |
| } |
| |
| free_track = kasan_get_free_track(cache, object, tag); |
| if (free_track) { |
| print_track(free_track, "Freed"); |
| pr_err("\n"); |
| } |
| |
| #ifdef CONFIG_KASAN_GENERIC |
| if (!alloc_meta) |
| return; |
| if (alloc_meta->aux_stack[0]) { |
| pr_err("Last potentially related work creation:\n"); |
| print_stack(alloc_meta->aux_stack[0]); |
| pr_err("\n"); |
| } |
| if (alloc_meta->aux_stack[1]) { |
| pr_err("Second to last potentially related work creation:\n"); |
| print_stack(alloc_meta->aux_stack[1]); |
| pr_err("\n"); |
| } |
| #endif |
| } |
| |
| static void describe_object(struct kmem_cache *cache, void *object, |
| const void *addr, u8 tag) |
| { |
| if (kasan_stack_collection_enabled()) |
| describe_object_stacks(cache, object, addr, tag); |
| describe_object_addr(cache, object, addr); |
| } |
| |
| static inline bool kernel_or_module_addr(const void *addr) |
| { |
| if (is_kernel((unsigned long)addr)) |
| return true; |
| if (is_module_address((unsigned long)addr)) |
| return true; |
| return false; |
| } |
| |
| static inline bool init_task_stack_addr(const void *addr) |
| { |
| return addr >= (void *)&init_thread_union.stack && |
| (addr <= (void *)&init_thread_union.stack + |
| sizeof(init_thread_union.stack)); |
| } |
| |
| static void print_address_description(void *addr, u8 tag) |
| { |
| struct page *page = kasan_addr_to_page(addr); |
| |
| dump_stack_lvl(KERN_ERR); |
| pr_err("\n"); |
| |
| if (page && PageSlab(page)) { |
| struct kmem_cache *cache = page->slab_cache; |
| void *object = nearest_obj(cache, page, addr); |
| |
| describe_object(cache, object, addr, tag); |
| } |
| |
| if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) { |
| pr_err("The buggy address belongs to the variable:\n"); |
| pr_err(" %pS\n", addr); |
| } |
| |
| if (page) { |
| pr_err("The buggy address belongs to the page:\n"); |
| dump_page(page, "kasan: bad access detected"); |
| } |
| |
| kasan_print_address_stack_frame(addr); |
| } |
| |
| static bool meta_row_is_guilty(const void *row, const void *addr) |
| { |
| return (row <= addr) && (addr < row + META_MEM_BYTES_PER_ROW); |
| } |
| |
| static int meta_pointer_offset(const void *row, const void *addr) |
| { |
| /* |
| * Memory state around the buggy address: |
| * ff00ff00ff00ff00: 00 00 00 05 fe fe fe fe fe fe fe fe fe fe fe fe |
| * ... |
| * |
| * The length of ">ff00ff00ff00ff00: " is |
| * 3 + (BITS_PER_LONG / 8) * 2 chars. |
| * The length of each granule metadata is 2 bytes |
| * plus 1 byte for space. |
| */ |
| return 3 + (BITS_PER_LONG / 8) * 2 + |
| (addr - row) / KASAN_GRANULE_SIZE * 3 + 1; |
| } |
| |
| static void print_memory_metadata(const void *addr) |
| { |
| int i; |
| void *row; |
| |
| row = (void *)round_down((unsigned long)addr, META_MEM_BYTES_PER_ROW) |
| - META_ROWS_AROUND_ADDR * META_MEM_BYTES_PER_ROW; |
| |
| pr_err("Memory state around the buggy address:\n"); |
| |
| for (i = -META_ROWS_AROUND_ADDR; i <= META_ROWS_AROUND_ADDR; i++) { |
| char buffer[4 + (BITS_PER_LONG / 8) * 2]; |
| char metadata[META_BYTES_PER_ROW]; |
| |
| snprintf(buffer, sizeof(buffer), |
| (i == 0) ? ">%px: " : " %px: ", row); |
| |
| /* |
| * We should not pass a shadow pointer to generic |
| * function, because generic functions may try to |
| * access kasan mapping for the passed address. |
| */ |
| kasan_metadata_fetch_row(&metadata[0], row); |
| |
| print_hex_dump(KERN_ERR, buffer, |
| DUMP_PREFIX_NONE, META_BYTES_PER_ROW, 1, |
| metadata, META_BYTES_PER_ROW, 0); |
| |
| if (meta_row_is_guilty(row, addr)) |
| pr_err("%*c\n", meta_pointer_offset(row, addr), '^'); |
| |
| row += META_MEM_BYTES_PER_ROW; |
| } |
| } |
| |
| static bool report_enabled(void) |
| { |
| #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) |
| if (current->kasan_depth) |
| return false; |
| #endif |
| if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) |
| return true; |
| return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); |
| } |
| |
| #if IS_ENABLED(CONFIG_KUNIT) |
| static void kasan_update_kunit_status(struct kunit *cur_test, bool sync) |
| { |
| struct kunit_resource *resource; |
| struct kunit_kasan_status *status; |
| |
| resource = kunit_find_named_resource(cur_test, "kasan_status"); |
| |
| if (!resource) { |
| kunit_set_failure(cur_test); |
| return; |
| } |
| |
| status = (struct kunit_kasan_status *)resource->data; |
| WRITE_ONCE(status->report_found, true); |
| WRITE_ONCE(status->sync_fault, sync); |
| kunit_put_resource(resource); |
| } |
| #endif /* IS_ENABLED(CONFIG_KUNIT) */ |
| |
| void kasan_report_invalid_free(void *object, unsigned long ip) |
| { |
| unsigned long flags; |
| u8 tag = get_tag(object); |
| |
| object = kasan_reset_tag(object); |
| |
| #if IS_ENABLED(CONFIG_KUNIT) |
| if (current->kunit_test) |
| kasan_update_kunit_status(current->kunit_test, true); |
| #endif /* IS_ENABLED(CONFIG_KUNIT) */ |
| |
| start_report(&flags); |
| pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip); |
| kasan_print_tags(tag, object); |
| pr_err("\n"); |
| print_address_description(object, tag); |
| pr_err("\n"); |
| print_memory_metadata(object); |
| end_report(&flags, (unsigned long)object); |
| } |
| |
| #ifdef CONFIG_KASAN_HW_TAGS |
| void kasan_report_async(void) |
| { |
| unsigned long flags; |
| |
| #if IS_ENABLED(CONFIG_KUNIT) |
| if (current->kunit_test) |
| kasan_update_kunit_status(current->kunit_test, false); |
| #endif /* IS_ENABLED(CONFIG_KUNIT) */ |
| |
| start_report(&flags); |
| pr_err("BUG: KASAN: invalid-access\n"); |
| pr_err("Asynchronous mode enabled: no access details available\n"); |
| pr_err("\n"); |
| dump_stack_lvl(KERN_ERR); |
| end_report(&flags, 0); |
| } |
| #endif /* CONFIG_KASAN_HW_TAGS */ |
| |
| static void __kasan_report(unsigned long addr, size_t size, bool is_write, |
| unsigned long ip) |
| { |
| struct kasan_access_info info; |
| void *tagged_addr; |
| void *untagged_addr; |
| unsigned long flags; |
| |
| #if IS_ENABLED(CONFIG_KUNIT) |
| if (current->kunit_test) |
| kasan_update_kunit_status(current->kunit_test, true); |
| #endif /* IS_ENABLED(CONFIG_KUNIT) */ |
| |
| disable_trace_on_warning(); |
| |
| tagged_addr = (void *)addr; |
| untagged_addr = kasan_reset_tag(tagged_addr); |
| |
| info.access_addr = tagged_addr; |
| if (addr_has_metadata(untagged_addr)) |
| info.first_bad_addr = |
| kasan_find_first_bad_addr(tagged_addr, size); |
| else |
| info.first_bad_addr = untagged_addr; |
| info.access_size = size; |
| info.is_write = is_write; |
| info.ip = ip; |
| |
| start_report(&flags); |
| |
| print_error_description(&info); |
| if (addr_has_metadata(untagged_addr)) |
| kasan_print_tags(get_tag(tagged_addr), info.first_bad_addr); |
| pr_err("\n"); |
| |
| if (addr_has_metadata(untagged_addr)) { |
| print_address_description(untagged_addr, get_tag(tagged_addr)); |
| pr_err("\n"); |
| print_memory_metadata(info.first_bad_addr); |
| } else { |
| dump_stack_lvl(KERN_ERR); |
| } |
| |
| end_report(&flags, addr); |
| } |
| |
| bool kasan_report(unsigned long addr, size_t size, bool is_write, |
| unsigned long ip) |
| { |
| unsigned long flags = user_access_save(); |
| bool ret = false; |
| |
| if (likely(report_enabled())) { |
| __kasan_report(addr, size, is_write, ip); |
| ret = true; |
| } |
| |
| user_access_restore(flags); |
| |
| return ret; |
| } |
| |
| #ifdef CONFIG_KASAN_INLINE |
| /* |
| * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high |
| * canonical half of the address space) cause out-of-bounds shadow memory reads |
| * before the actual access. For addresses in the low canonical half of the |
| * address space, as well as most non-canonical addresses, that out-of-bounds |
| * shadow memory access lands in the non-canonical part of the address space. |
| * Help the user figure out what the original bogus pointer was. |
| */ |
| void kasan_non_canonical_hook(unsigned long addr) |
| { |
| unsigned long orig_addr; |
| const char *bug_type; |
| |
| if (addr < KASAN_SHADOW_OFFSET) |
| return; |
| |
| orig_addr = (addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT; |
| /* |
| * For faults near the shadow address for NULL, we can be fairly certain |
| * that this is a KASAN shadow memory access. |
| * For faults that correspond to shadow for low canonical addresses, we |
| * can still be pretty sure - that shadow region is a fairly narrow |
| * chunk of the non-canonical address space. |
| * But faults that look like shadow for non-canonical addresses are a |
| * really large chunk of the address space. In that case, we still |
| * print the decoded address, but make it clear that this is not |
| * necessarily what's actually going on. |
| */ |
| if (orig_addr < PAGE_SIZE) |
| bug_type = "null-ptr-deref"; |
| else if (orig_addr < TASK_SIZE) |
| bug_type = "probably user-memory-access"; |
| else |
| bug_type = "maybe wild-memory-access"; |
| pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type, |
| orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1); |
| } |
| #endif |