1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * This file contains generic 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
 37void *find_first_bad_addr(void *addr, size_t size)
 38{
 39	void *p = addr;
 40
 41	while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
 42		p += KASAN_SHADOW_SCALE_SIZE;
 43	return p;
 44}
 45
 46static const char *get_shadow_bug_type(struct kasan_access_info *info)
 47{
 48	const char *bug_type = "unknown-crash";
 49	u8 *shadow_addr;
 50
 51	shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
 52
 53	/*
 54	 * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
 55	 * at the next shadow byte to determine the type of the bad access.
 56	 */
 57	if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
 58		shadow_addr++;
 59
 60	switch (*shadow_addr) {
 61	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
 62		/*
 63		 * In theory it's still possible to see these shadow values
 64		 * due to a data race in the kernel code.
 65		 */
 66		bug_type = "out-of-bounds";
 67		break;
 68	case KASAN_PAGE_REDZONE:
 69	case KASAN_KMALLOC_REDZONE:
 70		bug_type = "slab-out-of-bounds";
 71		break;
 72	case KASAN_GLOBAL_REDZONE:
 73		bug_type = "global-out-of-bounds";
 74		break;
 75	case KASAN_STACK_LEFT:
 76	case KASAN_STACK_MID:
 77	case KASAN_STACK_RIGHT:
 78	case KASAN_STACK_PARTIAL:
 79		bug_type = "stack-out-of-bounds";
 80		break;
 81	case KASAN_FREE_PAGE:
 82	case KASAN_KMALLOC_FREE:
 83	case KASAN_KMALLOC_FREETRACK:
 84		bug_type = "use-after-free";
 85		break;
 86	case KASAN_ALLOCA_LEFT:
 87	case KASAN_ALLOCA_RIGHT:
 88		bug_type = "alloca-out-of-bounds";
 89		break;
 90	case KASAN_VMALLOC_INVALID:
 91		bug_type = "vmalloc-out-of-bounds";
 92		break;
 93	}
 94
 95	return bug_type;
 96}
 97
 98static const char *get_wild_bug_type(struct kasan_access_info *info)
 99{
100	const char *bug_type = "unknown-crash";
101
102	if ((unsigned long)info->access_addr < PAGE_SIZE)
103		bug_type = "null-ptr-deref";
104	else if ((unsigned long)info->access_addr < TASK_SIZE)
105		bug_type = "user-memory-access";
106	else
107		bug_type = "wild-memory-access";
108
109	return bug_type;
110}
111
112const char *get_bug_type(struct kasan_access_info *info)
113{
114	/*
115	 * If access_size is a negative number, then it has reason to be
116	 * defined as out-of-bounds bug type.
117	 *
118	 * Casting negative numbers to size_t would indeed turn up as
119	 * a large size_t and its value will be larger than ULONG_MAX/2,
120	 * so that this can qualify as out-of-bounds.
121	 */
122	if (info->access_addr + info->access_size < info->access_addr)
123		return "out-of-bounds";
124
125	if (addr_has_shadow(info->access_addr))
126		return get_shadow_bug_type(info);
127	return get_wild_bug_type(info);
128}
129
130#define DEFINE_ASAN_REPORT_LOAD(size)                     \
131void __asan_report_load##size##_noabort(unsigned long addr) \
132{                                                         \
133	kasan_report(addr, size, false, _RET_IP_);	  \
134}                                                         \
135EXPORT_SYMBOL(__asan_report_load##size##_noabort)
136
137#define DEFINE_ASAN_REPORT_STORE(size)                     \
138void __asan_report_store##size##_noabort(unsigned long addr) \
139{                                                          \
140	kasan_report(addr, size, true, _RET_IP_);	   \
141}                                                          \
142EXPORT_SYMBOL(__asan_report_store##size##_noabort)
143
144DEFINE_ASAN_REPORT_LOAD(1);
145DEFINE_ASAN_REPORT_LOAD(2);
146DEFINE_ASAN_REPORT_LOAD(4);
147DEFINE_ASAN_REPORT_LOAD(8);
148DEFINE_ASAN_REPORT_LOAD(16);
149DEFINE_ASAN_REPORT_STORE(1);
150DEFINE_ASAN_REPORT_STORE(2);
151DEFINE_ASAN_REPORT_STORE(4);
152DEFINE_ASAN_REPORT_STORE(8);
153DEFINE_ASAN_REPORT_STORE(16);
154
155void __asan_report_load_n_noabort(unsigned long addr, size_t size)
156{
157	kasan_report(addr, size, false, _RET_IP_);
158}
159EXPORT_SYMBOL(__asan_report_load_n_noabort);
160
161void __asan_report_store_n_noabort(unsigned long addr, size_t size)
162{
163	kasan_report(addr, size, true, _RET_IP_);
164}
165EXPORT_SYMBOL(__asan_report_store_n_noabort);