1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
|
// SPDX-License-Identifier: GPL-2.0
/*
* KMSAN hooks for kernel subsystems.
*
* These functions handle creation of KMSAN metadata for memory allocations.
*
* Copyright (C) 2018-2022 Google LLC
* Author: Alexander Potapenko <glider@google.com>
*
*/
#include <linux/cacheflush.h>
#include <linux/gfp.h>
#include <linux/kmsan.h>
#include <linux/mm.h>
#include <linux/mm_types.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include "../internal.h"
#include "../slab.h"
#include "kmsan.h"
/*
* Instrumented functions shouldn't be called under
* kmsan_enter_runtime()/kmsan_leave_runtime(), because this will lead to
* skipping effects of functions like memset() inside instrumented code.
*/
void kmsan_task_create(struct task_struct *task)
{
kmsan_enter_runtime();
kmsan_internal_task_create(task);
kmsan_leave_runtime();
}
void kmsan_task_exit(struct task_struct *task)
{
struct kmsan_ctx *ctx = &task->kmsan_ctx;
if (!kmsan_enabled || kmsan_in_runtime())
return;
ctx->allow_reporting = false;
}
void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags)
{
if (unlikely(object == NULL))
return;
if (!kmsan_enabled || kmsan_in_runtime())
return;
/*
* There's a ctor or this is an RCU cache - do nothing. The memory
* status hasn't changed since last use.
*/
if (s->ctor || (s->flags & SLAB_TYPESAFE_BY_RCU))
return;
kmsan_enter_runtime();
if (flags & __GFP_ZERO)
kmsan_internal_unpoison_memory(object, s->object_size,
KMSAN_POISON_CHECK);
else
kmsan_internal_poison_memory(object, s->object_size, flags,
KMSAN_POISON_CHECK);
kmsan_leave_runtime();
}
void kmsan_slab_free(struct kmem_cache *s, void *object)
{
if (!kmsan_enabled || kmsan_in_runtime())
return;
/* RCU slabs could be legally used after free within the RCU period */
if (unlikely(s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)))
return;
/*
* If there's a constructor, freed memory must remain in the same state
* until the next allocation. We cannot save its state to detect
* use-after-free bugs, instead we just keep it unpoisoned.
*/
if (s->ctor)
return;
kmsan_enter_runtime();
kmsan_internal_poison_memory(object, s->object_size, GFP_KERNEL,
KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
kmsan_leave_runtime();
}
void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
{
if (unlikely(ptr == NULL))
return;
if (!kmsan_enabled || kmsan_in_runtime())
return;
kmsan_enter_runtime();
if (flags & __GFP_ZERO)
kmsan_internal_unpoison_memory((void *)ptr, size,
/*checked*/ true);
else
kmsan_internal_poison_memory((void *)ptr, size, flags,
KMSAN_POISON_CHECK);
kmsan_leave_runtime();
}
void kmsan_kfree_large(const void *ptr)
{
struct page *page;
if (!kmsan_enabled || kmsan_in_runtime())
return;
kmsan_enter_runtime();
page = virt_to_head_page((void *)ptr);
KMSAN_WARN_ON(ptr != page_address(page));
kmsan_internal_poison_memory((void *)ptr,
PAGE_SIZE << compound_order(page),
GFP_KERNEL,
KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
kmsan_leave_runtime();
}
static unsigned long vmalloc_shadow(unsigned long addr)
{
return (unsigned long)kmsan_get_metadata((void *)addr,
KMSAN_META_SHADOW);
}
static unsigned long vmalloc_origin(unsigned long addr)
{
return (unsigned long)kmsan_get_metadata((void *)addr,
KMSAN_META_ORIGIN);
}
void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end)
{
__vunmap_range_noflush(vmalloc_shadow(start), vmalloc_shadow(end));
__vunmap_range_noflush(vmalloc_origin(start), vmalloc_origin(end));
flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
}
/*
* This function creates new shadow/origin pages for the physical pages mapped
* into the virtual memory. If those physical pages already had shadow/origin,
* those are ignored.
*/
void kmsan_ioremap_page_range(unsigned long start, unsigned long end,
phys_addr_t phys_addr, pgprot_t prot,
unsigned int page_shift)
{
gfp_t gfp_mask = GFP_KERNEL | __GFP_ZERO;
struct page *shadow, *origin;
unsigned long off = 0;
int nr;
if (!kmsan_enabled || kmsan_in_runtime())
return;
nr = (end - start) / PAGE_SIZE;
kmsan_enter_runtime();
for (int i = 0; i < nr; i++, off += PAGE_SIZE) {
shadow = alloc_pages(gfp_mask, 1);
origin = alloc_pages(gfp_mask, 1);
__vmap_pages_range_noflush(
vmalloc_shadow(start + off),
vmalloc_shadow(start + off + PAGE_SIZE), prot, &shadow,
PAGE_SHIFT);
__vmap_pages_range_noflush(
vmalloc_origin(start + off),
vmalloc_origin(start + off + PAGE_SIZE), prot, &origin,
PAGE_SHIFT);
}
flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
kmsan_leave_runtime();
}
void kmsan_iounmap_page_range(unsigned long start, unsigned long end)
{
unsigned long v_shadow, v_origin;
struct page *shadow, *origin;
int nr;
if (!kmsan_enabled || kmsan_in_runtime())
return;
nr = (end - start) / PAGE_SIZE;
kmsan_enter_runtime();
v_shadow = (unsigned long)vmalloc_shadow(start);
v_origin = (unsigned long)vmalloc_origin(start);
for (int i = 0; i < nr;
i++, v_shadow += PAGE_SIZE, v_origin += PAGE_SIZE) {
shadow = kmsan_vmalloc_to_page_or_null((void *)v_shadow);
origin = kmsan_vmalloc_to_page_or_null((void *)v_origin);
__vunmap_range_noflush(v_shadow, vmalloc_shadow(end));
__vunmap_range_noflush(v_origin, vmalloc_origin(end));
if (shadow)
__free_pages(shadow, 1);
if (origin)
__free_pages(origin, 1);
}
flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
kmsan_leave_runtime();
}
/* Functions from kmsan-checks.h follow. */
void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
{
if (!kmsan_enabled || kmsan_in_runtime())
return;
kmsan_enter_runtime();
/* The users may want to poison/unpoison random memory. */
kmsan_internal_poison_memory((void *)address, size, flags,
KMSAN_POISON_NOCHECK);
kmsan_leave_runtime();
}
EXPORT_SYMBOL(kmsan_poison_memory);
void kmsan_unpoison_memory(const void *address, size_t size)
{
unsigned long ua_flags;
if (!kmsan_enabled || kmsan_in_runtime())
return;
ua_flags = user_access_save();
kmsan_enter_runtime();
/* The users may want to poison/unpoison random memory. */
kmsan_internal_unpoison_memory((void *)address, size,
KMSAN_POISON_NOCHECK);
kmsan_leave_runtime();
user_access_restore(ua_flags);
}
EXPORT_SYMBOL(kmsan_unpoison_memory);
void kmsan_check_memory(const void *addr, size_t size)
{
if (!kmsan_enabled)
return;
return kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,
REASON_ANY);
}
EXPORT_SYMBOL(kmsan_check_memory);
|
