1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * This file contains hardware tag-based KASAN specific error reporting code. 4 * 5 * Copyright (c) 2020 Google, Inc. 6 * Author: Andrey Konovalov <andreyknvl@google.com> 7 */ 8 9 #include <linux/kasan.h> 10 #include <linux/kernel.h> 11 #include <linux/memory.h> 12 #include <linux/mm.h> 13 #include <linux/string.h> 14 #include <linux/types.h> 15 16 #include "kasan.h" 17 18 const void *kasan_find_first_bad_addr(const void *addr, size_t size) 19 { 20 /* 21 * Hardware Tag-Based KASAN only calls this function for normal memory 22 * accesses, and thus addr points precisely to the first bad address 23 * with an invalid (and present) memory tag. Therefore: 24 * 1. Return the address as is without walking memory tags. 25 * 2. Skip the addr_has_metadata check. 26 */ 27 return kasan_reset_tag(addr); 28 } 29 30 size_t kasan_get_alloc_size(void *object, struct kmem_cache *cache) 31 { 32 size_t size = 0; 33 int i = 0; 34 u8 memory_tag; 35 36 /* 37 * Skip the addr_has_metadata check, as this function only operates on 38 * slab memory, which must have metadata. 39 */ 40 41 /* 42 * The loop below returns 0 for freed objects, for which KASAN cannot 43 * calculate the allocation size based on the metadata. 44 */ 45 while (size < cache->object_size) { 46 memory_tag = hw_get_mem_tag(object + i * KASAN_GRANULE_SIZE); 47 if (memory_tag != KASAN_TAG_INVALID) 48 size += KASAN_GRANULE_SIZE; 49 else 50 return size; 51 i++; 52 } 53 54 return cache->object_size; 55 } 56 57 void kasan_metadata_fetch_row(char *buffer, void *row) 58 { 59 int i; 60 61 for (i = 0; i < META_BYTES_PER_ROW; i++) 62 buffer[i] = hw_get_mem_tag(row + i * KASAN_GRANULE_SIZE); 63 } 64 65 void kasan_print_tags(u8 addr_tag, const void *addr) 66 { 67 u8 memory_tag = hw_get_mem_tag((void *)addr); 68 69 pr_err("Pointer tag: [%02x], memory tag: [%02x]\n", 70 addr_tag, memory_tag); 71 } 72