| /* |
| * This file contains 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 <adech.fo@gmail.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| */ |
| |
| #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 <asm/sections.h> |
| |
| #include "kasan.h" |
| #include "../slab.h" |
| |
| /* Shadow layout customization. */ |
| #define SHADOW_BYTES_PER_BLOCK 1 |
| #define SHADOW_BLOCKS_PER_ROW 16 |
| #define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK) |
| #define SHADOW_ROWS_AROUND_ADDR 2 |
| |
| static const void *find_first_bad_addr(const void *addr, size_t size) |
| { |
| u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr); |
| const void *first_bad_addr = addr; |
| |
| while (!shadow_val && first_bad_addr < addr + size) { |
| first_bad_addr += KASAN_SHADOW_SCALE_SIZE; |
| shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr); |
| } |
| return first_bad_addr; |
| } |
| |
| static bool addr_has_shadow(struct kasan_access_info *info) |
| { |
| return (info->access_addr >= |
| kasan_shadow_to_mem((void *)KASAN_SHADOW_START)); |
| } |
| |
| static const char *get_shadow_bug_type(struct kasan_access_info *info) |
| { |
| const char *bug_type = "unknown-crash"; |
| u8 *shadow_addr; |
| |
| info->first_bad_addr = find_first_bad_addr(info->access_addr, |
| info->access_size); |
| |
| shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr); |
| |
| /* |
| * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look |
| * at the next shadow byte to determine the type of the bad access. |
| */ |
| if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1) |
| shadow_addr++; |
| |
| switch (*shadow_addr) { |
| case 0 ... KASAN_SHADOW_SCALE_SIZE - 1: |
| /* |
| * In theory it's still possible to see these shadow values |
| * due to a data race in the kernel code. |
| */ |
| bug_type = "out-of-bounds"; |
| break; |
| case KASAN_PAGE_REDZONE: |
| case KASAN_KMALLOC_REDZONE: |
| bug_type = "slab-out-of-bounds"; |
| break; |
| case KASAN_GLOBAL_REDZONE: |
| bug_type = "global-out-of-bounds"; |
| break; |
| case KASAN_STACK_LEFT: |
| case KASAN_STACK_MID: |
| case KASAN_STACK_RIGHT: |
| case KASAN_STACK_PARTIAL: |
| bug_type = "stack-out-of-bounds"; |
| break; |
| case KASAN_FREE_PAGE: |
| case KASAN_KMALLOC_FREE: |
| bug_type = "use-after-free"; |
| break; |
| case KASAN_USE_AFTER_SCOPE: |
| bug_type = "use-after-scope"; |
| break; |
| } |
| |
| return bug_type; |
| } |
| |
| static const char *get_wild_bug_type(struct kasan_access_info *info) |
| { |
| const char *bug_type = "unknown-crash"; |
| |
| if ((unsigned long)info->access_addr < PAGE_SIZE) |
| bug_type = "null-ptr-deref"; |
| else if ((unsigned long)info->access_addr < TASK_SIZE) |
| bug_type = "user-memory-access"; |
| else |
| bug_type = "wild-memory-access"; |
| |
| return bug_type; |
| } |
| |
| static const char *get_bug_type(struct kasan_access_info *info) |
| { |
| if (addr_has_shadow(info)) |
| return get_shadow_bug_type(info); |
| return get_wild_bug_type(info); |
| } |
| |
| static void print_error_description(struct kasan_access_info *info) |
| { |
| const char *bug_type = get_bug_type(info); |
| |
| pr_err("BUG: KASAN: %s in %pS\n", |
| bug_type, (void *)info->ip); |
| 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)); |
| } |
| |
| static inline bool kernel_or_module_addr(const void *addr) |
| { |
| if (addr >= (void *)_stext && addr < (void *)_end) |
| 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 DEFINE_SPINLOCK(report_lock); |
| |
| static void kasan_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 kasan_end_report(unsigned long *flags) |
| { |
| pr_err("==================================================================\n"); |
| add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); |
| spin_unlock_irqrestore(&report_lock, *flags); |
| if (panic_on_warn) |
| panic("panic_on_warn set ...\n"); |
| kasan_enable_current(); |
| } |
| |
| static void print_track(struct kasan_track *track, const char *prefix) |
| { |
| pr_err("%s by task %u:\n", prefix, track->pid); |
| if (track->stack) { |
| struct stack_trace trace; |
| |
| depot_fetch_stack(track->stack, &trace); |
| print_stack_trace(&trace, 0); |
| } else { |
| pr_err("(stack is not available)\n"); |
| } |
| } |
| |
| static struct page *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(struct kmem_cache *cache, void *object, |
| const void *addr) |
| { |
| struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); |
| |
| if (cache->flags & SLAB_KASAN) { |
| print_track(&alloc_info->alloc_track, "Allocated"); |
| pr_err("\n"); |
| print_track(&alloc_info->free_track, "Freed"); |
| pr_err("\n"); |
| } |
| |
| describe_object_addr(cache, object, addr); |
| } |
| |
| static void print_address_description(void *addr) |
| { |
| struct page *page = addr_to_page(addr); |
| |
| dump_stack(); |
| 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); |
| } |
| |
| 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"); |
| } |
| } |
| |
| static bool row_is_guilty(const void *row, const void *guilty) |
| { |
| return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); |
| } |
| |
| static int shadow_pointer_offset(const void *row, const void *shadow) |
| { |
| /* The length of ">ff00ff00ff00ff00: " is |
| * 3 + (BITS_PER_LONG/8)*2 chars. |
| */ |
| return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 + |
| (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1; |
| } |
| |
| static void print_shadow_for_address(const void *addr) |
| { |
| int i; |
| const void *shadow = kasan_mem_to_shadow(addr); |
| const void *shadow_row; |
| |
| shadow_row = (void *)round_down((unsigned long)shadow, |
| SHADOW_BYTES_PER_ROW) |
| - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW; |
| |
| pr_err("Memory state around the buggy address:\n"); |
| |
| for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) { |
| const void *kaddr = kasan_shadow_to_mem(shadow_row); |
| char buffer[4 + (BITS_PER_LONG/8)*2]; |
| char shadow_buf[SHADOW_BYTES_PER_ROW]; |
| |
| snprintf(buffer, sizeof(buffer), |
| (i == 0) ? ">%px: " : " %px: ", kaddr); |
| /* |
| * We should not pass a shadow pointer to generic |
| * function, because generic functions may try to |
| * access kasan mapping for the passed address. |
| */ |
| memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW); |
| print_hex_dump(KERN_ERR, buffer, |
| DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1, |
| shadow_buf, SHADOW_BYTES_PER_ROW, 0); |
| |
| if (row_is_guilty(shadow_row, shadow)) |
| pr_err("%*c\n", |
| shadow_pointer_offset(shadow_row, shadow), |
| '^'); |
| |
| shadow_row += SHADOW_BYTES_PER_ROW; |
| } |
| } |
| |
| void kasan_report_double_free(struct kmem_cache *cache, void *object, |
| void *ip) |
| { |
| unsigned long flags; |
| |
| kasan_start_report(&flags); |
| pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", ip); |
| pr_err("\n"); |
| print_address_description(object); |
| pr_err("\n"); |
| print_shadow_for_address(object); |
| kasan_end_report(&flags); |
| } |
| |
| static void kasan_report_error(struct kasan_access_info *info) |
| { |
| unsigned long flags; |
| |
| kasan_start_report(&flags); |
| |
| print_error_description(info); |
| pr_err("\n"); |
| |
| if (!addr_has_shadow(info)) { |
| dump_stack(); |
| } else { |
| print_address_description((void *)info->access_addr); |
| pr_err("\n"); |
| print_shadow_for_address(info->first_bad_addr); |
| } |
| |
| kasan_end_report(&flags); |
| } |
| |
| static unsigned long kasan_flags; |
| |
| #define KASAN_BIT_REPORTED 0 |
| #define KASAN_BIT_MULTI_SHOT 1 |
| |
| 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 inline bool kasan_report_enabled(void) |
| { |
| if (current->kasan_depth) |
| return false; |
| if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) |
| return true; |
| return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); |
| } |
| |
| void kasan_report(unsigned long addr, size_t size, |
| bool is_write, unsigned long ip) |
| { |
| struct kasan_access_info info; |
| |
| if (likely(!kasan_report_enabled())) |
| return; |
| |
| disable_trace_on_warning(); |
| |
| info.access_addr = (void *)addr; |
| info.first_bad_addr = (void *)addr; |
| info.access_size = size; |
| info.is_write = is_write; |
| info.ip = ip; |
| |
| kasan_report_error(&info); |
| } |
| |
| |
| #define DEFINE_ASAN_REPORT_LOAD(size) \ |
| void __asan_report_load##size##_noabort(unsigned long addr) \ |
| { \ |
| kasan_report(addr, size, false, _RET_IP_); \ |
| } \ |
| EXPORT_SYMBOL(__asan_report_load##size##_noabort) |
| |
| #define DEFINE_ASAN_REPORT_STORE(size) \ |
| void __asan_report_store##size##_noabort(unsigned long addr) \ |
| { \ |
| kasan_report(addr, size, true, _RET_IP_); \ |
| } \ |
| EXPORT_SYMBOL(__asan_report_store##size##_noabort) |
| |
| DEFINE_ASAN_REPORT_LOAD(1); |
| DEFINE_ASAN_REPORT_LOAD(2); |
| DEFINE_ASAN_REPORT_LOAD(4); |
| DEFINE_ASAN_REPORT_LOAD(8); |
| DEFINE_ASAN_REPORT_LOAD(16); |
| DEFINE_ASAN_REPORT_STORE(1); |
| DEFINE_ASAN_REPORT_STORE(2); |
| DEFINE_ASAN_REPORT_STORE(4); |
| DEFINE_ASAN_REPORT_STORE(8); |
| DEFINE_ASAN_REPORT_STORE(16); |
| |
| void __asan_report_load_n_noabort(unsigned long addr, size_t size) |
| { |
| kasan_report(addr, size, false, _RET_IP_); |
| } |
| EXPORT_SYMBOL(__asan_report_load_n_noabort); |
| |
| void __asan_report_store_n_noabort(unsigned long addr, size_t size) |
| { |
| kasan_report(addr, size, true, _RET_IP_); |
| } |
| EXPORT_SYMBOL(__asan_report_store_n_noabort); |