root/mm/kasan/tags_report.c

DEFINITIONS

1. get_bug_type
2. find_first_bad_addr
3. print_tags

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * This file contains tag-based KASAN specific error reporting code.
   4  *
   5  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
   6  * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
   7  *
   8  * Some code borrowed from https://github.com/xairy/kasan-prototype by
   9  *        Andrey Konovalov <andreyknvl@gmail.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  *
  15  */
  16 
  17 #include <linux/bitops.h>
  18 #include <linux/ftrace.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/mm.h>
  22 #include <linux/printk.h>
  23 #include <linux/sched.h>
  24 #include <linux/slab.h>
  25 #include <linux/stackdepot.h>
  26 #include <linux/stacktrace.h>
  27 #include <linux/string.h>
  28 #include <linux/types.h>
  29 #include <linux/kasan.h>
  30 #include <linux/module.h>
  31 
  32 #include <asm/sections.h>
  33 
  34 #include "kasan.h"
  35 #include "../slab.h"
  36 
  37 const char *get_bug_type(struct kasan_access_info *info)
  38 {
  39 #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
  40         struct kasan_alloc_meta *alloc_meta;
  41         struct kmem_cache *cache;
  42         struct page *page;
  43         const void *addr;
  44         void *object;
  45         u8 tag;
  46         int i;
  47 
  48         tag = get_tag(info->access_addr);
  49         addr = reset_tag(info->access_addr);
  50         page = kasan_addr_to_page(addr);
  51         if (page && PageSlab(page)) {
  52                 cache = page->slab_cache;
  53                 object = nearest_obj(cache, page, (void *)addr);
  54                 alloc_meta = get_alloc_info(cache, object);
  55 
  56                 for (i = 0; i < KASAN_NR_FREE_STACKS; i++)
  57                         if (alloc_meta->free_pointer_tag[i] == tag)
  58                                 return "use-after-free";
  59                 return "out-of-bounds";
  60         }
  61 
  62 #endif
  63         return "invalid-access";
  64 }
  65 
  66 void *find_first_bad_addr(void *addr, size_t size)
  67 {
  68         u8 tag = get_tag(addr);
  69         void *p = reset_tag(addr);
  70         void *end = p + size;
  71 
  72         while (p < end && tag == *(u8 *)kasan_mem_to_shadow(p))
  73                 p += KASAN_SHADOW_SCALE_SIZE;
  74         return p;
  75 }
  76 
  77 void print_tags(u8 addr_tag, const void *addr)
  78 {
  79         u8 *shadow = (u8 *)kasan_mem_to_shadow(addr);
  80 
  81         pr_err("Pointer tag: [%02x], memory tag: [%02x]\n", addr_tag, *shadow);
  82 }