2 * This file contains error reporting code.
4 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
5 * Author: Andrey Ryabinin <a.ryabinin@samsung.com>
7 * Some of code borrowed from https://github.com/xairy/linux by
8 * Andrey Konovalov <adech.fo@gmail.com>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
16 #include <linux/kernel.h>
18 #include <linux/printk.h>
19 #include <linux/sched.h>
20 #include <linux/slab.h>
21 #include <linux/stacktrace.h>
22 #include <linux/string.h>
23 #include <linux/types.h>
24 #include <linux/kasan.h>
29 /* Shadow layout customization. */
30 #define SHADOW_BYTES_PER_BLOCK 1
31 #define SHADOW_BLOCKS_PER_ROW 16
32 #define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
33 #define SHADOW_ROWS_AROUND_ADDR 2
35 static const void *find_first_bad_addr(const void *addr, size_t size)
37 u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
38 const void *first_bad_addr = addr;
40 while (!shadow_val && first_bad_addr < addr + size) {
41 first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
42 shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
44 return first_bad_addr;
47 static void print_error_description(struct kasan_access_info *info)
49 const char *bug_type = "unknown crash";
52 info->first_bad_addr = find_first_bad_addr(info->access_addr,
55 shadow_val = *(u8 *)kasan_mem_to_shadow(info->first_bad_addr);
59 case KASAN_KMALLOC_FREE:
60 bug_type = "use after free";
62 case KASAN_PAGE_REDZONE:
63 case KASAN_KMALLOC_REDZONE:
64 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
65 bug_type = "out of bounds access";
69 pr_err("BUG: KASan: %s in %pS at addr %p\n",
70 bug_type, (void *)info->ip,
72 pr_err("%s of size %zu by task %s/%d\n",
73 info->is_write ? "Write" : "Read",
74 info->access_size, current->comm, task_pid_nr(current));
77 static void print_address_description(struct kasan_access_info *info)
79 const void *addr = info->access_addr;
81 if ((addr >= (void *)PAGE_OFFSET) &&
82 (addr < high_memory)) {
83 struct page *page = virt_to_head_page(addr);
87 struct kmem_cache *cache = page->slab_cache;
90 object = virt_to_obj(cache, page_address(page), addr);
91 last_object = page_address(page) +
92 page->objects * cache->size;
94 if (unlikely(object > last_object))
95 object = last_object; /* we hit into padding */
97 object_err(cache, page, object,
98 "kasan: bad access detected");
101 dump_page(page, "kasan: bad access detected");
107 static bool row_is_guilty(const void *row, const void *guilty)
109 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
112 static int shadow_pointer_offset(const void *row, const void *shadow)
114 /* The length of ">ff00ff00ff00ff00: " is
115 * 3 + (BITS_PER_LONG/8)*2 chars.
117 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
118 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
121 static void print_shadow_for_address(const void *addr)
124 const void *shadow = kasan_mem_to_shadow(addr);
125 const void *shadow_row;
127 shadow_row = (void *)round_down((unsigned long)shadow,
128 SHADOW_BYTES_PER_ROW)
129 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
131 pr_err("Memory state around the buggy address:\n");
133 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
134 const void *kaddr = kasan_shadow_to_mem(shadow_row);
135 char buffer[4 + (BITS_PER_LONG/8)*2];
137 snprintf(buffer, sizeof(buffer),
138 (i == 0) ? ">%p: " : " %p: ", kaddr);
140 kasan_disable_current();
141 print_hex_dump(KERN_ERR, buffer,
142 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
143 shadow_row, SHADOW_BYTES_PER_ROW, 0);
144 kasan_enable_current();
146 if (row_is_guilty(shadow_row, shadow))
148 shadow_pointer_offset(shadow_row, shadow),
151 shadow_row += SHADOW_BYTES_PER_ROW;
155 static DEFINE_SPINLOCK(report_lock);
157 void kasan_report_error(struct kasan_access_info *info)
161 spin_lock_irqsave(&report_lock, flags);
162 pr_err("================================="
163 "=================================\n");
164 print_error_description(info);
165 print_address_description(info);
166 print_shadow_for_address(info->first_bad_addr);
167 pr_err("================================="
168 "=================================\n");
169 spin_unlock_irqrestore(&report_lock, flags);
172 void kasan_report_user_access(struct kasan_access_info *info)
176 spin_lock_irqsave(&report_lock, flags);
177 pr_err("================================="
178 "=================================\n");
179 pr_err("BUG: KASan: user-memory-access on address %p\n",
181 pr_err("%s of size %zu by task %s/%d\n",
182 info->is_write ? "Write" : "Read",
183 info->access_size, current->comm, task_pid_nr(current));
185 pr_err("================================="
186 "=================================\n");
187 spin_unlock_irqrestore(&report_lock, flags);
190 void kasan_report(unsigned long addr, size_t size,
191 bool is_write, unsigned long ip)
193 struct kasan_access_info info;
195 if (likely(!kasan_enabled()))
198 info.access_addr = (void *)addr;
199 info.access_size = size;
200 info.is_write = is_write;
202 kasan_report_error(&info);
206 #define DEFINE_ASAN_REPORT_LOAD(size) \
207 void __asan_report_load##size##_noabort(unsigned long addr) \
209 kasan_report(addr, size, false, _RET_IP_); \
211 EXPORT_SYMBOL(__asan_report_load##size##_noabort)
213 #define DEFINE_ASAN_REPORT_STORE(size) \
214 void __asan_report_store##size##_noabort(unsigned long addr) \
216 kasan_report(addr, size, true, _RET_IP_); \
218 EXPORT_SYMBOL(__asan_report_store##size##_noabort)
220 DEFINE_ASAN_REPORT_LOAD(1);
221 DEFINE_ASAN_REPORT_LOAD(2);
222 DEFINE_ASAN_REPORT_LOAD(4);
223 DEFINE_ASAN_REPORT_LOAD(8);
224 DEFINE_ASAN_REPORT_LOAD(16);
225 DEFINE_ASAN_REPORT_STORE(1);
226 DEFINE_ASAN_REPORT_STORE(2);
227 DEFINE_ASAN_REPORT_STORE(4);
228 DEFINE_ASAN_REPORT_STORE(8);
229 DEFINE_ASAN_REPORT_STORE(16);
231 void __asan_report_load_n_noabort(unsigned long addr, size_t size)
233 kasan_report(addr, size, false, _RET_IP_);
235 EXPORT_SYMBOL(__asan_report_load_n_noabort);
237 void __asan_report_store_n_noabort(unsigned long addr, size_t size)
239 kasan_report(addr, size, true, _RET_IP_);
241 EXPORT_SYMBOL(__asan_report_store_n_noabort);