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1// SPDX-License-Identifier: GPL-2.02/*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 by9 * Andrey Konovalov <andreyknvl@gmail.com>10 */11 12#include <linux/bitops.h>13#include <linux/ftrace.h>14#include <linux/init.h>15#include <linux/kernel.h>16#include <linux/mm.h>17#include <linux/printk.h>18#include <linux/sched.h>19#include <linux/sched/task_stack.h>20#include <linux/slab.h>21#include <linux/stackdepot.h>22#include <linux/stacktrace.h>23#include <linux/string.h>24#include <linux/types.h>25#include <linux/kasan.h>26#include <linux/module.h>27 28#include <asm/sections.h>29 30#include "kasan.h"31#include "../slab.h"32 33const void *kasan_find_first_bad_addr(const void *addr, size_t size)34{35 const void *p = addr;36 37 if (!addr_has_metadata(p))38 return p;39 40 while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))41 p += KASAN_GRANULE_SIZE;42 43 return p;44}45 46size_t kasan_get_alloc_size(void *object, struct kmem_cache *cache)47{48 size_t size = 0;49 u8 *shadow;50 51 /*52 * Skip the addr_has_metadata check, as this function only operates on53 * slab memory, which must have metadata.54 */55 56 /*57 * The loop below returns 0 for freed objects, for which KASAN cannot58 * calculate the allocation size based on the metadata.59 */60 shadow = (u8 *)kasan_mem_to_shadow(object);61 while (size < cache->object_size) {62 if (*shadow == 0)63 size += KASAN_GRANULE_SIZE;64 else if (*shadow >= 1 && *shadow <= KASAN_GRANULE_SIZE - 1)65 return size + *shadow;66 else67 return size;68 shadow++;69 }70 71 return cache->object_size;72}73 74static const char *get_shadow_bug_type(struct kasan_report_info *info)75{76 const char *bug_type = "unknown-crash";77 u8 *shadow_addr;78 79 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);80 81 /*82 * If shadow byte value is in [0, KASAN_GRANULE_SIZE) we can look83 * at the next shadow byte to determine the type of the bad access.84 */85 if (*shadow_addr > 0 && *shadow_addr <= KASAN_GRANULE_SIZE - 1)86 shadow_addr++;87 88 switch (*shadow_addr) {89 case 0 ... KASAN_GRANULE_SIZE - 1:90 /*91 * In theory it's still possible to see these shadow values92 * due to a data race in the kernel code.93 */94 bug_type = "out-of-bounds";95 break;96 case KASAN_PAGE_REDZONE:97 case KASAN_SLAB_REDZONE:98 bug_type = "slab-out-of-bounds";99 break;100 case KASAN_GLOBAL_REDZONE:101 bug_type = "global-out-of-bounds";102 break;103 case KASAN_STACK_LEFT:104 case KASAN_STACK_MID:105 case KASAN_STACK_RIGHT:106 case KASAN_STACK_PARTIAL:107 bug_type = "stack-out-of-bounds";108 break;109 case KASAN_PAGE_FREE:110 bug_type = "use-after-free";111 break;112 case KASAN_SLAB_FREE:113 case KASAN_SLAB_FREE_META:114 bug_type = "slab-use-after-free";115 break;116 case KASAN_ALLOCA_LEFT:117 case KASAN_ALLOCA_RIGHT:118 bug_type = "alloca-out-of-bounds";119 break;120 case KASAN_VMALLOC_INVALID:121 bug_type = "vmalloc-out-of-bounds";122 break;123 }124 125 return bug_type;126}127 128static const char *get_wild_bug_type(struct kasan_report_info *info)129{130 const char *bug_type = "unknown-crash";131 132 if ((unsigned long)info->access_addr < PAGE_SIZE)133 bug_type = "null-ptr-deref";134 else if ((unsigned long)info->access_addr < TASK_SIZE)135 bug_type = "user-memory-access";136 else137 bug_type = "wild-memory-access";138 139 return bug_type;140}141 142static const char *get_bug_type(struct kasan_report_info *info)143{144 /*145 * If access_size is a negative number, then it has reason to be146 * defined as out-of-bounds bug type.147 *148 * Casting negative numbers to size_t would indeed turn up as149 * a large size_t and its value will be larger than ULONG_MAX/2,150 * so that this can qualify as out-of-bounds.151 */152 if (info->access_addr + info->access_size < info->access_addr)153 return "out-of-bounds";154 155 if (addr_has_metadata(info->access_addr))156 return get_shadow_bug_type(info);157 return get_wild_bug_type(info);158}159 160void kasan_complete_mode_report_info(struct kasan_report_info *info)161{162 struct kasan_alloc_meta *alloc_meta;163 struct kasan_free_meta *free_meta;164 165 if (!info->bug_type)166 info->bug_type = get_bug_type(info);167 168 if (!info->cache || !info->object)169 return;170 171 alloc_meta = kasan_get_alloc_meta(info->cache, info->object);172 if (alloc_meta)173 memcpy(&info->alloc_track, &alloc_meta->alloc_track,174 sizeof(info->alloc_track));175 176 if (*(u8 *)kasan_mem_to_shadow(info->object) == KASAN_SLAB_FREE_META) {177 /* Free meta must be present with KASAN_SLAB_FREE_META. */178 free_meta = kasan_get_free_meta(info->cache, info->object);179 memcpy(&info->free_track, &free_meta->free_track,180 sizeof(info->free_track));181 }182}183 184void kasan_metadata_fetch_row(char *buffer, void *row)185{186 memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW);187}188 189void kasan_print_aux_stacks(struct kmem_cache *cache, const void *object)190{191 struct kasan_alloc_meta *alloc_meta;192 193 alloc_meta = kasan_get_alloc_meta(cache, object);194 if (!alloc_meta)195 return;196 197 if (alloc_meta->aux_stack[0]) {198 pr_err("Last potentially related work creation:\n");199 stack_depot_print(alloc_meta->aux_stack[0]);200 pr_err("\n");201 }202 if (alloc_meta->aux_stack[1]) {203 pr_err("Second to last potentially related work creation:\n");204 stack_depot_print(alloc_meta->aux_stack[1]);205 pr_err("\n");206 }207}208 209#ifdef CONFIG_KASAN_STACK210static bool __must_check tokenize_frame_descr(const char **frame_descr,211 char *token, size_t max_tok_len,212 unsigned long *value)213{214 const char *sep = strchr(*frame_descr, ' ');215 216 if (sep == NULL)217 sep = *frame_descr + strlen(*frame_descr);218 219 if (token != NULL) {220 const size_t tok_len = sep - *frame_descr;221 222 if (tok_len + 1 > max_tok_len) {223 pr_err("internal error: frame description too long: %s\n",224 *frame_descr);225 return false;226 }227 228 /* Copy token (+ 1 byte for '\0'). */229 strscpy(token, *frame_descr, tok_len + 1);230 }231 232 /* Advance frame_descr past separator. */233 *frame_descr = sep + 1;234 235 if (value != NULL && kstrtoul(token, 10, value)) {236 pr_err("internal error: not a valid number: %s\n", token);237 return false;238 }239 240 return true;241}242 243static void print_decoded_frame_descr(const char *frame_descr)244{245 /*246 * We need to parse the following string:247 * "n alloc_1 alloc_2 ... alloc_n"248 * where alloc_i looks like249 * "offset size len name"250 * or "offset size len name:line".251 */252 253 char token[64];254 unsigned long num_objects;255 256 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),257 &num_objects))258 return;259 260 pr_err("\n");261 pr_err("This frame has %lu %s:\n", num_objects,262 num_objects == 1 ? "object" : "objects");263 264 while (num_objects--) {265 unsigned long offset;266 unsigned long size;267 268 /* access offset */269 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),270 &offset))271 return;272 /* access size */273 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),274 &size))275 return;276 /* name length (unused) */277 if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL))278 return;279 /* object name */280 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),281 NULL))282 return;283 284 /* Strip line number; without filename it's not very helpful. */285 strreplace(token, ':', '\0');286 287 /* Finally, print object information. */288 pr_err(" [%lu, %lu) '%s'", offset, offset + size, token);289 }290}291 292/* Returns true only if the address is on the current task's stack. */293static bool __must_check get_address_stack_frame_info(const void *addr,294 unsigned long *offset,295 const char **frame_descr,296 const void **frame_pc)297{298 unsigned long aligned_addr;299 unsigned long mem_ptr;300 const u8 *shadow_bottom;301 const u8 *shadow_ptr;302 const unsigned long *frame;303 304 BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP));305 306 aligned_addr = round_down((unsigned long)addr, sizeof(long));307 mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE);308 shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr);309 shadow_bottom = kasan_mem_to_shadow(end_of_stack(current));310 311 while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) {312 shadow_ptr--;313 mem_ptr -= KASAN_GRANULE_SIZE;314 }315 316 while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) {317 shadow_ptr--;318 mem_ptr -= KASAN_GRANULE_SIZE;319 }320 321 if (shadow_ptr < shadow_bottom)322 return false;323 324 frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE);325 if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) {326 pr_err("internal error: frame has invalid marker: %lu\n",327 frame[0]);328 return false;329 }330 331 *offset = (unsigned long)addr - (unsigned long)frame;332 *frame_descr = (const char *)frame[1];333 *frame_pc = (void *)frame[2];334 335 return true;336}337 338void kasan_print_address_stack_frame(const void *addr)339{340 unsigned long offset;341 const char *frame_descr;342 const void *frame_pc;343 344 if (WARN_ON(!object_is_on_stack(addr)))345 return;346 347 pr_err("The buggy address belongs to stack of task %s/%d\n",348 current->comm, task_pid_nr(current));349 350 if (!get_address_stack_frame_info(addr, &offset, &frame_descr,351 &frame_pc))352 return;353 354 pr_err(" and is located at offset %lu in frame:\n", offset);355 pr_err(" %pS\n", frame_pc);356 357 if (!frame_descr)358 return;359 360 print_decoded_frame_descr(frame_descr);361}362#endif /* CONFIG_KASAN_STACK */363 364#define DEFINE_ASAN_REPORT_LOAD(size) \365void __asan_report_load##size##_noabort(void *addr) \366{ \367 kasan_report(addr, size, false, _RET_IP_); \368} \369EXPORT_SYMBOL(__asan_report_load##size##_noabort)370 371#define DEFINE_ASAN_REPORT_STORE(size) \372void __asan_report_store##size##_noabort(void *addr) \373{ \374 kasan_report(addr, size, true, _RET_IP_); \375} \376EXPORT_SYMBOL(__asan_report_store##size##_noabort)377 378DEFINE_ASAN_REPORT_LOAD(1);379DEFINE_ASAN_REPORT_LOAD(2);380DEFINE_ASAN_REPORT_LOAD(4);381DEFINE_ASAN_REPORT_LOAD(8);382DEFINE_ASAN_REPORT_LOAD(16);383DEFINE_ASAN_REPORT_STORE(1);384DEFINE_ASAN_REPORT_STORE(2);385DEFINE_ASAN_REPORT_STORE(4);386DEFINE_ASAN_REPORT_STORE(8);387DEFINE_ASAN_REPORT_STORE(16);388 389void __asan_report_load_n_noabort(void *addr, ssize_t size)390{391 kasan_report(addr, size, false, _RET_IP_);392}393EXPORT_SYMBOL(__asan_report_load_n_noabort);394 395void __asan_report_store_n_noabort(void *addr, ssize_t size)396{397 kasan_report(addr, size, true, _RET_IP_);398}399EXPORT_SYMBOL(__asan_report_store_n_noabort);400