// SPDX-License-Identifier: GPL-2.0
/*
* This file contains generic KASAN specific error reporting code.
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
* Author: Andrey Ryabinin <[email protected]>
*
* Some code borrowed from https://github.com/xairy/kasan-prototype by
* Andrey Konovalov <[email protected]>
*/
#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/sched/task_stack.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"
const void *kasan_find_first_bad_addr(const void *addr, size_t size)
{
const void *p = addr;
if (!addr_has_metadata(p))
return p;
while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
p += KASAN_GRANULE_SIZE;
return p;
}
size_t kasan_get_alloc_size(void *object, struct kmem_cache *cache)
{
size_t size = 0;
u8 *shadow;
/*
* Skip the addr_has_metadata check, as this function only operates on
* slab memory, which must have metadata.
*/
/*
* The loop below returns 0 for freed objects, for which KASAN cannot
* calculate the allocation size based on the metadata.
*/
shadow = (u8 *)kasan_mem_to_shadow(object);
while (size < cache->object_size) {
if (*shadow == 0)
size += KASAN_GRANULE_SIZE;
else if (*shadow >= 1 && *shadow <= KASAN_GRANULE_SIZE - 1)
return size + *shadow;
else
return size;
shadow++;
}
return cache->object_size;
}
static const char *get_shadow_bug_type(struct kasan_report_info *info)
{
const char *bug_type = "unknown-crash";
u8 *shadow_addr;
shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
/*
* If shadow byte value is in [0, KASAN_GRANULE_SIZE) we can look
* at the next shadow byte to determine the type of the bad access.
*/
if (*shadow_addr > 0 && *shadow_addr <= KASAN_GRANULE_SIZE - 1)
shadow_addr++;
switch (*shadow_addr) {
case 0 ... KASAN_GRANULE_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_SLAB_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_PAGE_FREE:
bug_type = "use-after-free";
break;
case KASAN_SLAB_FREE:
case KASAN_SLAB_FREE_META:
bug_type = "slab-use-after-free";
break;
case KASAN_ALLOCA_LEFT:
case KASAN_ALLOCA_RIGHT:
bug_type = "alloca-out-of-bounds";
break;
case KASAN_VMALLOC_INVALID:
bug_type = "vmalloc-out-of-bounds";
break;
}
return bug_type;
}
static const char *get_wild_bug_type(struct kasan_report_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_report_info *info)
{
/*
* If access_size is a negative number, then it has reason to be
* defined as out-of-bounds bug type.
*
* Casting negative numbers to size_t would indeed turn up as
* a large size_t and its value will be larger than ULONG_MAX/2,
* so that this can qualify as out-of-bounds.
*/
if (info->access_addr + info->access_size < info->access_addr)
return "out-of-bounds";
if (addr_has_metadata(info->access_addr))
return get_shadow_bug_type(info);
return get_wild_bug_type(info);
}
void kasan_complete_mode_report_info(struct kasan_report_info *info)
{
struct kasan_alloc_meta *alloc_meta;
struct kasan_free_meta *free_meta;
if (!info->bug_type)
info->bug_type = get_bug_type(info);
if (!info->cache || !info->object)
return;
alloc_meta = kasan_get_alloc_meta(info->cache, info->object);
if (alloc_meta)
memcpy(&info->alloc_track, &alloc_meta->alloc_track,
sizeof(info->alloc_track));
if (*(u8 *)kasan_mem_to_shadow(info->object) == KASAN_SLAB_FREE_META) {
/* Free meta must be present with KASAN_SLAB_FREE_META. */
free_meta = kasan_get_free_meta(info->cache, info->object);
memcpy(&info->free_track, &free_meta->free_track,
sizeof(info->free_track));
}
}
void kasan_metadata_fetch_row(char *buffer, void *row)
{
memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW);
}
void kasan_print_aux_stacks(struct kmem_cache *cache, const void *object)
{
struct kasan_alloc_meta *alloc_meta;
alloc_meta = kasan_get_alloc_meta(cache, object);
if (!alloc_meta)
return;
if (alloc_meta->aux_stack[0]) {
pr_err("Last potentially related work creation:\n");
stack_depot_print(alloc_meta->aux_stack[0]);
pr_err("\n");
}
if (alloc_meta->aux_stack[1]) {
pr_err("Second to last potentially related work creation:\n");
stack_depot_print(alloc_meta->aux_stack[1]);
pr_err("\n");
}
}
#ifdef CONFIG_KASAN_STACK
static bool __must_check tokenize_frame_descr(const char **frame_descr,
char *token, size_t max_tok_len,
unsigned long *value)
{
const char *sep = strchr(*frame_descr, ' ');
if (sep == NULL)
sep = *frame_descr + strlen(*frame_descr);
if (token != NULL) {
const size_t tok_len = sep - *frame_descr;
if (tok_len + 1 > max_tok_len) {
pr_err("internal error: frame description too long: %s\n",
*frame_descr);
return false;
}
/* Copy token (+ 1 byte for '\0'). */
strscpy(token, *frame_descr, tok_len + 1);
}
/* Advance frame_descr past separator. */
*frame_descr = sep + 1;
if (value != NULL && kstrtoul(token, 10, value)) {
pr_err("internal error: not a valid number: %s\n", token);
return false;
}
return true;
}
static void print_decoded_frame_descr(const char *frame_descr)
{
/*
* We need to parse the following string:
* "n alloc_1 alloc_2 ... alloc_n"
* where alloc_i looks like
* "offset size len name"
* or "offset size len name:line".
*/
char token[64];
unsigned long num_objects;
if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
&num_objects))
return;
pr_err("\n");
pr_err("This frame has %lu %s:\n", num_objects,
num_objects == 1 ? "object" : "objects");
while (num_objects--) {
unsigned long offset;
unsigned long size;
/* access offset */
if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
&offset))
return;
/* access size */
if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
&size))
return;
/* name length (unused) */
if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL))
return;
/* object name */
if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
NULL))
return;
/* Strip line number; without filename it's not very helpful. */
strreplace(token, ':', '\0');
/* Finally, print object information. */
pr_err(" [%lu, %lu) '%s'", offset, offset + size, token);
}
}
/* Returns true only if the address is on the current task's stack. */
static bool __must_check get_address_stack_frame_info(const void *addr,
unsigned long *offset,
const char **frame_descr,
const void **frame_pc)
{
unsigned long aligned_addr;
unsigned long mem_ptr;
const u8 *shadow_bottom;
const u8 *shadow_ptr;
const unsigned long *frame;
BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP));
aligned_addr = round_down((unsigned long)addr, sizeof(long));
mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE);
shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr);
shadow_bottom = kasan_mem_to_shadow(end_of_stack(current));
while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) {
shadow_ptr--;
mem_ptr -= KASAN_GRANULE_SIZE;
}
while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) {
shadow_ptr--;
mem_ptr -= KASAN_GRANULE_SIZE;
}
if (shadow_ptr < shadow_bottom)
return false;
frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE);
if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) {
pr_err("internal error: frame has invalid marker: %lu\n",
frame[0]);
return false;
}
*offset = (unsigned long)addr - (unsigned long)frame;
*frame_descr = (const char *)frame[1];
*frame_pc = (void *)frame[2];
return true;
}
void kasan_print_address_stack_frame(const void *addr)
{
unsigned long offset;
const char *frame_descr;
const void *frame_pc;
if (WARN_ON(!object_is_on_stack(addr)))
return;
pr_err("The buggy address belongs to stack of task %s/%d\n",
current->comm, task_pid_nr(current));
if (!get_address_stack_frame_info(addr, &offset, &frame_descr,
&frame_pc))
return;
pr_err(" and is located at offset %lu in frame:\n", offset);
pr_err(" %pS\n", frame_pc);
if (!frame_descr)
return;
print_decoded_frame_descr(frame_descr);
}
#endif /* CONFIG_KASAN_STACK */
#define DEFINE_ASAN_REPORT_LOAD(size) \
void __asan_report_load##size##_noabort(void *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(void *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(void *addr, ssize_t size)
{
kasan_report(addr, size, false, _RET_IP_);
}
EXPORT_SYMBOL(__asan_report_load_n_noabort);
void __asan_report_store_n_noabort(void *addr, ssize_t size)
{
kasan_report(addr, size, true, _RET_IP_);
}
EXPORT_SYMBOL(__asan_report_store_n_noabort);
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