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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * KMSAN hooks for kernel subsystems.
4 *
5 * These functions handle creation of KMSAN metadata for memory allocations.
6 *
7 * Copyright (C) 2018-2022 Google LLC
8 * Author: Alexander Potapenko <glider@google.com>
9 *
10 */
11
12#include <linux/cacheflush.h>
13#include <linux/dma-direction.h>
14#include <linux/gfp.h>
15#include <linux/kmsan.h>
16#include <linux/mm.h>
17#include <linux/mm_types.h>
18#include <linux/scatterlist.h>
19#include <linux/slab.h>
20#include <linux/uaccess.h>
21#include <linux/usb.h>
22
23#include "../internal.h"
24#include "../slab.h"
25#include "kmsan.h"
26
27/*
28 * Instrumented functions shouldn't be called under
29 * kmsan_enter_runtime()/kmsan_leave_runtime(), because this will lead to
30 * skipping effects of functions like memset() inside instrumented code.
31 */
32
33void kmsan_task_create(struct task_struct *task)
34{
35 kmsan_enter_runtime();
36 kmsan_internal_task_create(task);
37 kmsan_leave_runtime();
38}
39
40void kmsan_task_exit(struct task_struct *task)
41{
42 if (!kmsan_enabled || kmsan_in_runtime())
43 return;
44
45 kmsan_disable_current();
46}
47
48void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags)
49{
50 if (unlikely(object == NULL))
51 return;
52 if (!kmsan_enabled || kmsan_in_runtime())
53 return;
54 /*
55 * There's a ctor or this is an RCU cache - do nothing. The memory
56 * status hasn't changed since last use.
57 */
58 if (s->ctor || (s->flags & SLAB_TYPESAFE_BY_RCU))
59 return;
60
61 kmsan_enter_runtime();
62 if (flags & __GFP_ZERO)
63 kmsan_internal_unpoison_memory(object, s->object_size,
64 KMSAN_POISON_CHECK);
65 else
66 kmsan_internal_poison_memory(object, s->object_size, flags,
67 KMSAN_POISON_CHECK);
68 kmsan_leave_runtime();
69}
70
71void kmsan_slab_free(struct kmem_cache *s, void *object)
72{
73 if (!kmsan_enabled || kmsan_in_runtime())
74 return;
75
76 /* RCU slabs could be legally used after free within the RCU period */
77 if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU))
78 return;
79 /*
80 * If there's a constructor, freed memory must remain in the same state
81 * until the next allocation. We cannot save its state to detect
82 * use-after-free bugs, instead we just keep it unpoisoned.
83 */
84 if (s->ctor)
85 return;
86 kmsan_enter_runtime();
87 kmsan_internal_poison_memory(object, s->object_size, GFP_KERNEL,
88 KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
89 kmsan_leave_runtime();
90}
91
92void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
93{
94 if (unlikely(ptr == NULL))
95 return;
96 if (!kmsan_enabled || kmsan_in_runtime())
97 return;
98 kmsan_enter_runtime();
99 if (flags & __GFP_ZERO)
100 kmsan_internal_unpoison_memory((void *)ptr, size,
101 /*checked*/ true);
102 else
103 kmsan_internal_poison_memory((void *)ptr, size, flags,
104 KMSAN_POISON_CHECK);
105 kmsan_leave_runtime();
106}
107
108void kmsan_kfree_large(const void *ptr)
109{
110 struct page *page;
111
112 if (!kmsan_enabled || kmsan_in_runtime())
113 return;
114 kmsan_enter_runtime();
115 page = virt_to_head_page((void *)ptr);
116 KMSAN_WARN_ON(ptr != page_address(page));
117 kmsan_internal_poison_memory((void *)ptr,
118 page_size(page),
119 GFP_KERNEL,
120 KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
121 kmsan_leave_runtime();
122}
123
124static unsigned long vmalloc_shadow(unsigned long addr)
125{
126 return (unsigned long)kmsan_get_metadata((void *)addr,
127 KMSAN_META_SHADOW);
128}
129
130static unsigned long vmalloc_origin(unsigned long addr)
131{
132 return (unsigned long)kmsan_get_metadata((void *)addr,
133 KMSAN_META_ORIGIN);
134}
135
136void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end)
137{
138 __vunmap_range_noflush(vmalloc_shadow(start), vmalloc_shadow(end));
139 __vunmap_range_noflush(vmalloc_origin(start), vmalloc_origin(end));
140 flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
141 flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
142}
143
144/*
145 * This function creates new shadow/origin pages for the physical pages mapped
146 * into the virtual memory. If those physical pages already had shadow/origin,
147 * those are ignored.
148 */
149int kmsan_ioremap_page_range(unsigned long start, unsigned long end,
150 phys_addr_t phys_addr, pgprot_t prot,
151 unsigned int page_shift)
152{
153 gfp_t gfp_mask = GFP_KERNEL | __GFP_ZERO;
154 struct page *shadow, *origin;
155 unsigned long off = 0;
156 int nr, err = 0, clean = 0, mapped;
157
158 if (!kmsan_enabled || kmsan_in_runtime())
159 return 0;
160
161 nr = (end - start) / PAGE_SIZE;
162 kmsan_enter_runtime();
163 for (int i = 0; i < nr; i++, off += PAGE_SIZE, clean = i) {
164 shadow = alloc_pages(gfp_mask, 1);
165 origin = alloc_pages(gfp_mask, 1);
166 if (!shadow || !origin) {
167 err = -ENOMEM;
168 goto ret;
169 }
170 mapped = __vmap_pages_range_noflush(
171 vmalloc_shadow(start + off),
172 vmalloc_shadow(start + off + PAGE_SIZE), prot, &shadow,
173 PAGE_SHIFT);
174 if (mapped) {
175 err = mapped;
176 goto ret;
177 }
178 shadow = NULL;
179 mapped = __vmap_pages_range_noflush(
180 vmalloc_origin(start + off),
181 vmalloc_origin(start + off + PAGE_SIZE), prot, &origin,
182 PAGE_SHIFT);
183 if (mapped) {
184 __vunmap_range_noflush(
185 vmalloc_shadow(start + off),
186 vmalloc_shadow(start + off + PAGE_SIZE));
187 err = mapped;
188 goto ret;
189 }
190 origin = NULL;
191 }
192 /* Page mapping loop finished normally, nothing to clean up. */
193 clean = 0;
194
195ret:
196 if (clean > 0) {
197 /*
198 * Something went wrong. Clean up shadow/origin pages allocated
199 * on the last loop iteration, then delete mappings created
200 * during the previous iterations.
201 */
202 if (shadow)
203 __free_pages(shadow, 1);
204 if (origin)
205 __free_pages(origin, 1);
206 __vunmap_range_noflush(
207 vmalloc_shadow(start),
208 vmalloc_shadow(start + clean * PAGE_SIZE));
209 __vunmap_range_noflush(
210 vmalloc_origin(start),
211 vmalloc_origin(start + clean * PAGE_SIZE));
212 }
213 flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
214 flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
215 kmsan_leave_runtime();
216 return err;
217}
218
219void kmsan_iounmap_page_range(unsigned long start, unsigned long end)
220{
221 unsigned long v_shadow, v_origin;
222 struct page *shadow, *origin;
223 int nr;
224
225 if (!kmsan_enabled || kmsan_in_runtime())
226 return;
227
228 nr = (end - start) / PAGE_SIZE;
229 kmsan_enter_runtime();
230 v_shadow = (unsigned long)vmalloc_shadow(start);
231 v_origin = (unsigned long)vmalloc_origin(start);
232 for (int i = 0; i < nr;
233 i++, v_shadow += PAGE_SIZE, v_origin += PAGE_SIZE) {
234 shadow = kmsan_vmalloc_to_page_or_null((void *)v_shadow);
235 origin = kmsan_vmalloc_to_page_or_null((void *)v_origin);
236 __vunmap_range_noflush(v_shadow, vmalloc_shadow(end));
237 __vunmap_range_noflush(v_origin, vmalloc_origin(end));
238 if (shadow)
239 __free_pages(shadow, 1);
240 if (origin)
241 __free_pages(origin, 1);
242 }
243 flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
244 flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
245 kmsan_leave_runtime();
246}
247
248void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
249 size_t left)
250{
251 unsigned long ua_flags;
252
253 if (!kmsan_enabled || kmsan_in_runtime())
254 return;
255 /*
256 * At this point we've copied the memory already. It's hard to check it
257 * before copying, as the size of actually copied buffer is unknown.
258 */
259
260 /* copy_to_user() may copy zero bytes. No need to check. */
261 if (!to_copy)
262 return;
263 /* Or maybe copy_to_user() failed to copy anything. */
264 if (to_copy <= left)
265 return;
266
267 ua_flags = user_access_save();
268 if (!IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) ||
269 (u64)to < TASK_SIZE) {
270 /* This is a user memory access, check it. */
271 kmsan_internal_check_memory((void *)from, to_copy - left, to,
272 REASON_COPY_TO_USER);
273 } else {
274 /* Otherwise this is a kernel memory access. This happens when a
275 * compat syscall passes an argument allocated on the kernel
276 * stack to a real syscall.
277 * Don't check anything, just copy the shadow of the copied
278 * bytes.
279 */
280 kmsan_internal_memmove_metadata((void *)to, (void *)from,
281 to_copy - left);
282 }
283 user_access_restore(ua_flags);
284}
285EXPORT_SYMBOL(kmsan_copy_to_user);
286
287void kmsan_memmove(void *to, const void *from, size_t size)
288{
289 if (!kmsan_enabled || kmsan_in_runtime())
290 return;
291
292 kmsan_enter_runtime();
293 kmsan_internal_memmove_metadata(to, (void *)from, size);
294 kmsan_leave_runtime();
295}
296EXPORT_SYMBOL(kmsan_memmove);
297
298/* Helper function to check an URB. */
299void kmsan_handle_urb(const struct urb *urb, bool is_out)
300{
301 if (!urb)
302 return;
303 if (is_out)
304 kmsan_internal_check_memory(urb->transfer_buffer,
305 urb->transfer_buffer_length,
306 /*user_addr*/ NULL,
307 REASON_SUBMIT_URB);
308 else
309 kmsan_internal_unpoison_memory(urb->transfer_buffer,
310 urb->transfer_buffer_length,
311 /*checked*/ false);
312}
313EXPORT_SYMBOL_GPL(kmsan_handle_urb);
314
315static void kmsan_handle_dma_page(const void *addr, size_t size,
316 enum dma_data_direction dir)
317{
318 switch (dir) {
319 case DMA_BIDIRECTIONAL:
320 kmsan_internal_check_memory((void *)addr, size,
321 /*user_addr*/ NULL, REASON_ANY);
322 kmsan_internal_unpoison_memory((void *)addr, size,
323 /*checked*/ false);
324 break;
325 case DMA_TO_DEVICE:
326 kmsan_internal_check_memory((void *)addr, size,
327 /*user_addr*/ NULL, REASON_ANY);
328 break;
329 case DMA_FROM_DEVICE:
330 kmsan_internal_unpoison_memory((void *)addr, size,
331 /*checked*/ false);
332 break;
333 case DMA_NONE:
334 break;
335 }
336}
337
338/* Helper function to handle DMA data transfers. */
339void kmsan_handle_dma(struct page *page, size_t offset, size_t size,
340 enum dma_data_direction dir)
341{
342 u64 page_offset, to_go, addr;
343
344 if (PageHighMem(page))
345 return;
346 addr = (u64)page_address(page) + offset;
347 /*
348 * The kernel may occasionally give us adjacent DMA pages not belonging
349 * to the same allocation. Process them separately to avoid triggering
350 * internal KMSAN checks.
351 */
352 while (size > 0) {
353 page_offset = offset_in_page(addr);
354 to_go = min(PAGE_SIZE - page_offset, (u64)size);
355 kmsan_handle_dma_page((void *)addr, to_go, dir);
356 addr += to_go;
357 size -= to_go;
358 }
359}
360EXPORT_SYMBOL_GPL(kmsan_handle_dma);
361
362void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
363 enum dma_data_direction dir)
364{
365 struct scatterlist *item;
366 int i;
367
368 for_each_sg(sg, item, nents, i)
369 kmsan_handle_dma(sg_page(item), item->offset, item->length,
370 dir);
371}
372
373/* Functions from kmsan-checks.h follow. */
374
375/*
376 * To create an origin, kmsan_poison_memory() unwinds the stacks and stores it
377 * into the stack depot. This may cause deadlocks if done from within KMSAN
378 * runtime, therefore we bail out if kmsan_in_runtime().
379 */
380void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
381{
382 if (!kmsan_enabled || kmsan_in_runtime())
383 return;
384 kmsan_enter_runtime();
385 /* The users may want to poison/unpoison random memory. */
386 kmsan_internal_poison_memory((void *)address, size, flags,
387 KMSAN_POISON_NOCHECK);
388 kmsan_leave_runtime();
389}
390EXPORT_SYMBOL(kmsan_poison_memory);
391
392/*
393 * Unlike kmsan_poison_memory(), this function can be used from within KMSAN
394 * runtime, because it does not trigger allocations or call instrumented code.
395 */
396void kmsan_unpoison_memory(const void *address, size_t size)
397{
398 unsigned long ua_flags;
399
400 if (!kmsan_enabled)
401 return;
402
403 ua_flags = user_access_save();
404 /* The users may want to poison/unpoison random memory. */
405 kmsan_internal_unpoison_memory((void *)address, size,
406 KMSAN_POISON_NOCHECK);
407 user_access_restore(ua_flags);
408}
409EXPORT_SYMBOL(kmsan_unpoison_memory);
410
411/*
412 * Version of kmsan_unpoison_memory() called from IRQ entry functions.
413 */
414void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
415{
416 kmsan_unpoison_memory((void *)regs, sizeof(*regs));
417}
418
419void kmsan_check_memory(const void *addr, size_t size)
420{
421 if (!kmsan_enabled)
422 return;
423 return kmsan_internal_check_memory((void *)addr, size,
424 /*user_addr*/ NULL, REASON_ANY);
425}
426EXPORT_SYMBOL(kmsan_check_memory);
427
428void kmsan_enable_current(void)
429{
430 KMSAN_WARN_ON(current->kmsan_ctx.depth == 0);
431 current->kmsan_ctx.depth--;
432}
433EXPORT_SYMBOL(kmsan_enable_current);
434
435void kmsan_disable_current(void)
436{
437 current->kmsan_ctx.depth++;
438 KMSAN_WARN_ON(current->kmsan_ctx.depth == 0);
439}
440EXPORT_SYMBOL(kmsan_disable_current);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * KMSAN hooks for kernel subsystems.
4 *
5 * These functions handle creation of KMSAN metadata for memory allocations.
6 *
7 * Copyright (C) 2018-2022 Google LLC
8 * Author: Alexander Potapenko <glider@google.com>
9 *
10 */
11
12#include <linux/cacheflush.h>
13#include <linux/dma-direction.h>
14#include <linux/gfp.h>
15#include <linux/kmsan.h>
16#include <linux/mm.h>
17#include <linux/mm_types.h>
18#include <linux/scatterlist.h>
19#include <linux/slab.h>
20#include <linux/uaccess.h>
21#include <linux/usb.h>
22
23#include "../internal.h"
24#include "../slab.h"
25#include "kmsan.h"
26
27/*
28 * Instrumented functions shouldn't be called under
29 * kmsan_enter_runtime()/kmsan_leave_runtime(), because this will lead to
30 * skipping effects of functions like memset() inside instrumented code.
31 */
32
33void kmsan_task_create(struct task_struct *task)
34{
35 kmsan_enter_runtime();
36 kmsan_internal_task_create(task);
37 kmsan_leave_runtime();
38}
39
40void kmsan_task_exit(struct task_struct *task)
41{
42 struct kmsan_ctx *ctx = &task->kmsan_ctx;
43
44 if (!kmsan_enabled || kmsan_in_runtime())
45 return;
46
47 ctx->allow_reporting = false;
48}
49
50void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags)
51{
52 if (unlikely(object == NULL))
53 return;
54 if (!kmsan_enabled || kmsan_in_runtime())
55 return;
56 /*
57 * There's a ctor or this is an RCU cache - do nothing. The memory
58 * status hasn't changed since last use.
59 */
60 if (s->ctor || (s->flags & SLAB_TYPESAFE_BY_RCU))
61 return;
62
63 kmsan_enter_runtime();
64 if (flags & __GFP_ZERO)
65 kmsan_internal_unpoison_memory(object, s->object_size,
66 KMSAN_POISON_CHECK);
67 else
68 kmsan_internal_poison_memory(object, s->object_size, flags,
69 KMSAN_POISON_CHECK);
70 kmsan_leave_runtime();
71}
72
73void kmsan_slab_free(struct kmem_cache *s, void *object)
74{
75 if (!kmsan_enabled || kmsan_in_runtime())
76 return;
77
78 /* RCU slabs could be legally used after free within the RCU period */
79 if (unlikely(s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)))
80 return;
81 /*
82 * If there's a constructor, freed memory must remain in the same state
83 * until the next allocation. We cannot save its state to detect
84 * use-after-free bugs, instead we just keep it unpoisoned.
85 */
86 if (s->ctor)
87 return;
88 kmsan_enter_runtime();
89 kmsan_internal_poison_memory(object, s->object_size, GFP_KERNEL,
90 KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
91 kmsan_leave_runtime();
92}
93
94void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
95{
96 if (unlikely(ptr == NULL))
97 return;
98 if (!kmsan_enabled || kmsan_in_runtime())
99 return;
100 kmsan_enter_runtime();
101 if (flags & __GFP_ZERO)
102 kmsan_internal_unpoison_memory((void *)ptr, size,
103 /*checked*/ true);
104 else
105 kmsan_internal_poison_memory((void *)ptr, size, flags,
106 KMSAN_POISON_CHECK);
107 kmsan_leave_runtime();
108}
109
110void kmsan_kfree_large(const void *ptr)
111{
112 struct page *page;
113
114 if (!kmsan_enabled || kmsan_in_runtime())
115 return;
116 kmsan_enter_runtime();
117 page = virt_to_head_page((void *)ptr);
118 KMSAN_WARN_ON(ptr != page_address(page));
119 kmsan_internal_poison_memory((void *)ptr,
120 page_size(page),
121 GFP_KERNEL,
122 KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
123 kmsan_leave_runtime();
124}
125
126static unsigned long vmalloc_shadow(unsigned long addr)
127{
128 return (unsigned long)kmsan_get_metadata((void *)addr,
129 KMSAN_META_SHADOW);
130}
131
132static unsigned long vmalloc_origin(unsigned long addr)
133{
134 return (unsigned long)kmsan_get_metadata((void *)addr,
135 KMSAN_META_ORIGIN);
136}
137
138void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end)
139{
140 __vunmap_range_noflush(vmalloc_shadow(start), vmalloc_shadow(end));
141 __vunmap_range_noflush(vmalloc_origin(start), vmalloc_origin(end));
142 flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
143 flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
144}
145
146/*
147 * This function creates new shadow/origin pages for the physical pages mapped
148 * into the virtual memory. If those physical pages already had shadow/origin,
149 * those are ignored.
150 */
151int kmsan_ioremap_page_range(unsigned long start, unsigned long end,
152 phys_addr_t phys_addr, pgprot_t prot,
153 unsigned int page_shift)
154{
155 gfp_t gfp_mask = GFP_KERNEL | __GFP_ZERO;
156 struct page *shadow, *origin;
157 unsigned long off = 0;
158 int nr, err = 0, clean = 0, mapped;
159
160 if (!kmsan_enabled || kmsan_in_runtime())
161 return 0;
162
163 nr = (end - start) / PAGE_SIZE;
164 kmsan_enter_runtime();
165 for (int i = 0; i < nr; i++, off += PAGE_SIZE, clean = i) {
166 shadow = alloc_pages(gfp_mask, 1);
167 origin = alloc_pages(gfp_mask, 1);
168 if (!shadow || !origin) {
169 err = -ENOMEM;
170 goto ret;
171 }
172 mapped = __vmap_pages_range_noflush(
173 vmalloc_shadow(start + off),
174 vmalloc_shadow(start + off + PAGE_SIZE), prot, &shadow,
175 PAGE_SHIFT);
176 if (mapped) {
177 err = mapped;
178 goto ret;
179 }
180 shadow = NULL;
181 mapped = __vmap_pages_range_noflush(
182 vmalloc_origin(start + off),
183 vmalloc_origin(start + off + PAGE_SIZE), prot, &origin,
184 PAGE_SHIFT);
185 if (mapped) {
186 __vunmap_range_noflush(
187 vmalloc_shadow(start + off),
188 vmalloc_shadow(start + off + PAGE_SIZE));
189 err = mapped;
190 goto ret;
191 }
192 origin = NULL;
193 }
194 /* Page mapping loop finished normally, nothing to clean up. */
195 clean = 0;
196
197ret:
198 if (clean > 0) {
199 /*
200 * Something went wrong. Clean up shadow/origin pages allocated
201 * on the last loop iteration, then delete mappings created
202 * during the previous iterations.
203 */
204 if (shadow)
205 __free_pages(shadow, 1);
206 if (origin)
207 __free_pages(origin, 1);
208 __vunmap_range_noflush(
209 vmalloc_shadow(start),
210 vmalloc_shadow(start + clean * PAGE_SIZE));
211 __vunmap_range_noflush(
212 vmalloc_origin(start),
213 vmalloc_origin(start + clean * PAGE_SIZE));
214 }
215 flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
216 flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
217 kmsan_leave_runtime();
218 return err;
219}
220
221void kmsan_iounmap_page_range(unsigned long start, unsigned long end)
222{
223 unsigned long v_shadow, v_origin;
224 struct page *shadow, *origin;
225 int nr;
226
227 if (!kmsan_enabled || kmsan_in_runtime())
228 return;
229
230 nr = (end - start) / PAGE_SIZE;
231 kmsan_enter_runtime();
232 v_shadow = (unsigned long)vmalloc_shadow(start);
233 v_origin = (unsigned long)vmalloc_origin(start);
234 for (int i = 0; i < nr;
235 i++, v_shadow += PAGE_SIZE, v_origin += PAGE_SIZE) {
236 shadow = kmsan_vmalloc_to_page_or_null((void *)v_shadow);
237 origin = kmsan_vmalloc_to_page_or_null((void *)v_origin);
238 __vunmap_range_noflush(v_shadow, vmalloc_shadow(end));
239 __vunmap_range_noflush(v_origin, vmalloc_origin(end));
240 if (shadow)
241 __free_pages(shadow, 1);
242 if (origin)
243 __free_pages(origin, 1);
244 }
245 flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));
246 flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));
247 kmsan_leave_runtime();
248}
249
250void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
251 size_t left)
252{
253 unsigned long ua_flags;
254
255 if (!kmsan_enabled || kmsan_in_runtime())
256 return;
257 /*
258 * At this point we've copied the memory already. It's hard to check it
259 * before copying, as the size of actually copied buffer is unknown.
260 */
261
262 /* copy_to_user() may copy zero bytes. No need to check. */
263 if (!to_copy)
264 return;
265 /* Or maybe copy_to_user() failed to copy anything. */
266 if (to_copy <= left)
267 return;
268
269 ua_flags = user_access_save();
270 if ((u64)to < TASK_SIZE) {
271 /* This is a user memory access, check it. */
272 kmsan_internal_check_memory((void *)from, to_copy - left, to,
273 REASON_COPY_TO_USER);
274 } else {
275 /* Otherwise this is a kernel memory access. This happens when a
276 * compat syscall passes an argument allocated on the kernel
277 * stack to a real syscall.
278 * Don't check anything, just copy the shadow of the copied
279 * bytes.
280 */
281 kmsan_internal_memmove_metadata((void *)to, (void *)from,
282 to_copy - left);
283 }
284 user_access_restore(ua_flags);
285}
286EXPORT_SYMBOL(kmsan_copy_to_user);
287
288/* Helper function to check an URB. */
289void kmsan_handle_urb(const struct urb *urb, bool is_out)
290{
291 if (!urb)
292 return;
293 if (is_out)
294 kmsan_internal_check_memory(urb->transfer_buffer,
295 urb->transfer_buffer_length,
296 /*user_addr*/ 0, REASON_SUBMIT_URB);
297 else
298 kmsan_internal_unpoison_memory(urb->transfer_buffer,
299 urb->transfer_buffer_length,
300 /*checked*/ false);
301}
302EXPORT_SYMBOL_GPL(kmsan_handle_urb);
303
304static void kmsan_handle_dma_page(const void *addr, size_t size,
305 enum dma_data_direction dir)
306{
307 switch (dir) {
308 case DMA_BIDIRECTIONAL:
309 kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,
310 REASON_ANY);
311 kmsan_internal_unpoison_memory((void *)addr, size,
312 /*checked*/ false);
313 break;
314 case DMA_TO_DEVICE:
315 kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,
316 REASON_ANY);
317 break;
318 case DMA_FROM_DEVICE:
319 kmsan_internal_unpoison_memory((void *)addr, size,
320 /*checked*/ false);
321 break;
322 case DMA_NONE:
323 break;
324 }
325}
326
327/* Helper function to handle DMA data transfers. */
328void kmsan_handle_dma(struct page *page, size_t offset, size_t size,
329 enum dma_data_direction dir)
330{
331 u64 page_offset, to_go, addr;
332
333 if (PageHighMem(page))
334 return;
335 addr = (u64)page_address(page) + offset;
336 /*
337 * The kernel may occasionally give us adjacent DMA pages not belonging
338 * to the same allocation. Process them separately to avoid triggering
339 * internal KMSAN checks.
340 */
341 while (size > 0) {
342 page_offset = offset_in_page(addr);
343 to_go = min(PAGE_SIZE - page_offset, (u64)size);
344 kmsan_handle_dma_page((void *)addr, to_go, dir);
345 addr += to_go;
346 size -= to_go;
347 }
348}
349
350void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
351 enum dma_data_direction dir)
352{
353 struct scatterlist *item;
354 int i;
355
356 for_each_sg(sg, item, nents, i)
357 kmsan_handle_dma(sg_page(item), item->offset, item->length,
358 dir);
359}
360
361/* Functions from kmsan-checks.h follow. */
362void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
363{
364 if (!kmsan_enabled || kmsan_in_runtime())
365 return;
366 kmsan_enter_runtime();
367 /* The users may want to poison/unpoison random memory. */
368 kmsan_internal_poison_memory((void *)address, size, flags,
369 KMSAN_POISON_NOCHECK);
370 kmsan_leave_runtime();
371}
372EXPORT_SYMBOL(kmsan_poison_memory);
373
374void kmsan_unpoison_memory(const void *address, size_t size)
375{
376 unsigned long ua_flags;
377
378 if (!kmsan_enabled || kmsan_in_runtime())
379 return;
380
381 ua_flags = user_access_save();
382 kmsan_enter_runtime();
383 /* The users may want to poison/unpoison random memory. */
384 kmsan_internal_unpoison_memory((void *)address, size,
385 KMSAN_POISON_NOCHECK);
386 kmsan_leave_runtime();
387 user_access_restore(ua_flags);
388}
389EXPORT_SYMBOL(kmsan_unpoison_memory);
390
391/*
392 * Version of kmsan_unpoison_memory() that can be called from within the KMSAN
393 * runtime.
394 *
395 * Non-instrumented IRQ entry functions receive struct pt_regs from assembly
396 * code. Those regs need to be unpoisoned, otherwise using them will result in
397 * false positives.
398 * Using kmsan_unpoison_memory() is not an option in entry code, because the
399 * return value of in_task() is inconsistent - as a result, certain calls to
400 * kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensures that
401 * the registers are unpoisoned even if kmsan_in_runtime() is true in the early
402 * entry code.
403 */
404void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
405{
406 unsigned long ua_flags;
407
408 if (!kmsan_enabled)
409 return;
410
411 ua_flags = user_access_save();
412 kmsan_internal_unpoison_memory((void *)regs, sizeof(*regs),
413 KMSAN_POISON_NOCHECK);
414 user_access_restore(ua_flags);
415}
416
417void kmsan_check_memory(const void *addr, size_t size)
418{
419 if (!kmsan_enabled)
420 return;
421 return kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,
422 REASON_ANY);
423}
424EXPORT_SYMBOL(kmsan_check_memory);