[linux-block.git] / mm / kmsan / core.c

// SPDX-License-Identifier: GPL-2.0
/*
 * KMSAN runtime library.
 *
 * Copyright (C) 2017-2022 Google LLC
 * Author: Alexander Potapenko <glider@google.com>
 *
 */

#include <asm/page.h>
#include <linux/compiler.h>
#include <linux/export.h>
#include <linux/highmem.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kmsan_types.h>
#include <linux/memory.h>
#include <linux/mm.h>
#include <linux/mm_types.h>
#include <linux/mmzone.h>
#include <linux/percpu-defs.h>
#include <linux/preempt.h>
#include <linux/slab.h>
#include <linux/stackdepot.h>
#include <linux/stacktrace.h>
#include <linux/types.h>
#include <linux/vmalloc.h>

#include "../slab.h"
#include "kmsan.h"

bool kmsan_enabled __read_mostly;

/*
 * Per-CPU KMSAN context to be used in interrupts, where current->kmsan is
 * unavaliable.
 */
DEFINE_PER_CPU(struct kmsan_ctx, kmsan_percpu_ctx);

void kmsan_internal_poison_memory(void *address, size_t size, gfp_t flags,
				  unsigned int poison_flags)
{
	u32 extra_bits =
		kmsan_extra_bits(/*depth*/ 0, poison_flags & KMSAN_POISON_FREE);
	bool checked = poison_flags & KMSAN_POISON_CHECK;
	depot_stack_handle_t handle;

	handle = kmsan_save_stack_with_flags(flags, extra_bits);
	kmsan_internal_set_shadow_origin(address, size, -1, handle, checked);
}

void kmsan_internal_unpoison_memory(void *address, size_t size, bool checked)
{
	kmsan_internal_set_shadow_origin(address, size, 0, 0, checked);
}

depot_stack_handle_t kmsan_save_stack_with_flags(gfp_t flags,
						 unsigned int extra)
{
	unsigned long entries[KMSAN_STACK_DEPTH];
	unsigned int nr_entries;

	nr_entries = stack_trace_save(entries, KMSAN_STACK_DEPTH, 0);

	/* Don't sleep (see might_sleep_if() in __alloc_pages_nodemask()). */
	flags &= ~__GFP_DIRECT_RECLAIM;

	return __stack_depot_save(entries, nr_entries, extra, flags, true);
}

/* Copy the metadata following the memmove() behavior. */
void kmsan_internal_memmove_metadata(void *dst, void *src, size_t n)
{
	depot_stack_handle_t old_origin = 0, new_origin = 0;
	int src_slots, dst_slots, i, iter, step, skip_bits;
	depot_stack_handle_t *origin_src, *origin_dst;
	void *shadow_src, *shadow_dst;
	u32 *align_shadow_src, shadow;
	bool backwards;

	shadow_dst = kmsan_get_metadata(dst, KMSAN_META_SHADOW);
	if (!shadow_dst)
		return;
	KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(dst, n));

	shadow_src = kmsan_get_metadata(src, KMSAN_META_SHADOW);
	if (!shadow_src) {
		/*
		 * @src is untracked: zero out destination shadow, ignore the
		 * origins, we're done.
		 */
		__memset(shadow_dst, 0, n);
		return;
	}
	KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(src, n));

	__memmove(shadow_dst, shadow_src, n);

	origin_dst = kmsan_get_metadata(dst, KMSAN_META_ORIGIN);
	origin_src = kmsan_get_metadata(src, KMSAN_META_ORIGIN);
	KMSAN_WARN_ON(!origin_dst || !origin_src);
	src_slots = (ALIGN((u64)src + n, KMSAN_ORIGIN_SIZE) -
		     ALIGN_DOWN((u64)src, KMSAN_ORIGIN_SIZE)) /
		    KMSAN_ORIGIN_SIZE;
	dst_slots = (ALIGN((u64)dst + n, KMSAN_ORIGIN_SIZE) -
		     ALIGN_DOWN((u64)dst, KMSAN_ORIGIN_SIZE)) /
		    KMSAN_ORIGIN_SIZE;
	KMSAN_WARN_ON((src_slots < 1) || (dst_slots < 1));
	KMSAN_WARN_ON((src_slots - dst_slots > 1) ||
		      (dst_slots - src_slots < -1));

	backwards = dst > src;
	i = backwards ? min(src_slots, dst_slots) - 1 : 0;
	iter = backwards ? -1 : 1;

	align_shadow_src =
		(u32 *)ALIGN_DOWN((u64)shadow_src, KMSAN_ORIGIN_SIZE);
	for (step = 0; step < min(src_slots, dst_slots); step++, i += iter) {
		KMSAN_WARN_ON(i < 0);
		shadow = align_shadow_src[i];
		if (i == 0) {
			/*
			 * If @src isn't aligned on KMSAN_ORIGIN_SIZE, don't
			 * look at the first @src % KMSAN_ORIGIN_SIZE bytes
			 * of the first shadow slot.
			 */
			skip_bits = ((u64)src % KMSAN_ORIGIN_SIZE) * 8;
			shadow = (shadow >> skip_bits) << skip_bits;
		}
		if (i == src_slots - 1) {
			/*
			 * If @src + n isn't aligned on
			 * KMSAN_ORIGIN_SIZE, don't look at the last
			 * (@src + n) % KMSAN_ORIGIN_SIZE bytes of the
			 * last shadow slot.
			 */
			skip_bits = (((u64)src + n) % KMSAN_ORIGIN_SIZE) * 8;
			shadow = (shadow << skip_bits) >> skip_bits;
		}
		/*
		 * Overwrite the origin only if the corresponding
		 * shadow is nonempty.
		 */
		if (origin_src[i] && (origin_src[i] != old_origin) && shadow) {
			old_origin = origin_src[i];
			new_origin = kmsan_internal_chain_origin(old_origin);
			/*
			 * kmsan_internal_chain_origin() may return
			 * NULL, but we don't want to lose the previous
			 * origin value.
			 */
			if (!new_origin)
				new_origin = old_origin;
		}
		if (shadow)
			origin_dst[i] = new_origin;
		else
			origin_dst[i] = 0;
	}
	/*
	 * If dst_slots is greater than src_slots (i.e.
	 * dst_slots == src_slots + 1), there is an extra origin slot at the
	 * beginning or end of the destination buffer, for which we take the
	 * origin from the previous slot.
	 * This is only done if the part of the source shadow corresponding to
	 * slot is non-zero.
	 *
	 * E.g. if we copy 8 aligned bytes that are marked as uninitialized
	 * and have origins o111 and o222, to an unaligned buffer with offset 1,
	 * these two origins are copied to three origin slots, so one of then
	 * needs to be duplicated, depending on the copy direction (@backwards)
	 *
	 *   src shadow: |uuuu|uuuu|....|
	 *   src origin: |o111|o222|....|
	 *
	 * backwards = 0:
	 *   dst shadow: |.uuu|uuuu|u...|
	 *   dst origin: |....|o111|o222| - fill the empty slot with o111
	 * backwards = 1:
	 *   dst shadow: |.uuu|uuuu|u...|
	 *   dst origin: |o111|o222|....| - fill the empty slot with o222
	 */
	if (src_slots < dst_slots) {
		if (backwards) {
			shadow = align_shadow_src[src_slots - 1];
			skip_bits = (((u64)dst + n) % KMSAN_ORIGIN_SIZE) * 8;
			shadow = (shadow << skip_bits) >> skip_bits;
			if (shadow)
				/* src_slots > 0, therefore dst_slots is at least 2 */
				origin_dst[dst_slots - 1] =
					origin_dst[dst_slots - 2];
		} else {
			shadow = align_shadow_src[0];
			skip_bits = ((u64)dst % KMSAN_ORIGIN_SIZE) * 8;
			shadow = (shadow >> skip_bits) << skip_bits;
			if (shadow)
				origin_dst[0] = origin_dst[1];
		}
	}
}

depot_stack_handle_t kmsan_internal_chain_origin(depot_stack_handle_t id)
{
	unsigned long entries[3];
	u32 extra_bits;
	int depth;
	bool uaf;

	if (!id)
		return id;
	/*
	 * Make sure we have enough spare bits in @id to hold the UAF bit and
	 * the chain depth.
	 */
	BUILD_BUG_ON(
		(1 << STACK_DEPOT_EXTRA_BITS) <= (KMSAN_MAX_ORIGIN_DEPTH << 1));

	extra_bits = stack_depot_get_extra_bits(id);
	depth = kmsan_depth_from_eb(extra_bits);
	uaf = kmsan_uaf_from_eb(extra_bits);

	/*
	 * Stop chaining origins once the depth reached KMSAN_MAX_ORIGIN_DEPTH.
	 * This mostly happens in the case structures with uninitialized padding
	 * are copied around many times. Origin chains for such structures are
	 * usually periodic, and it does not make sense to fully store them.
	 */
	if (depth == KMSAN_MAX_ORIGIN_DEPTH)
		return id;

	depth++;
	extra_bits = kmsan_extra_bits(depth, uaf);

	entries[0] = KMSAN_CHAIN_MAGIC_ORIGIN;
	entries[1] = kmsan_save_stack_with_flags(GFP_ATOMIC, 0);
	entries[2] = id;
	/*
	 * @entries is a local var in non-instrumented code, so KMSAN does not
	 * know it is initialized. Explicitly unpoison it to avoid false
	 * positives when __stack_depot_save() passes it to instrumented code.
	 */
	kmsan_internal_unpoison_memory(entries, sizeof(entries), false);
	return __stack_depot_save(entries, ARRAY_SIZE(entries), extra_bits,
				  GFP_ATOMIC, true);
}

void kmsan_internal_set_shadow_origin(void *addr, size_t size, int b,
				      u32 origin, bool checked)
{
	u64 address = (u64)addr;
	void *shadow_start;
	u32 *origin_start;
	size_t pad = 0;

	KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(addr, size));
	shadow_start = kmsan_get_metadata(addr, KMSAN_META_SHADOW);
	if (!shadow_start) {
		/*
		 * kmsan_metadata_is_contiguous() is true, so either all shadow
		 * and origin pages are NULL, or all are non-NULL.
		 */
		if (checked) {
			pr_err("%s: not memsetting %ld bytes starting at %px, because the shadow is NULL\n",
			       __func__, size, addr);
			KMSAN_WARN_ON(true);
		}
		return;
	}
	__memset(shadow_start, b, size);

	if (!IS_ALIGNED(address, KMSAN_ORIGIN_SIZE)) {
		pad = address % KMSAN_ORIGIN_SIZE;
		address -= pad;
		size += pad;
	}
	size = ALIGN(size, KMSAN_ORIGIN_SIZE);
	origin_start =
		(u32 *)kmsan_get_metadata((void *)address, KMSAN_META_ORIGIN);

	for (int i = 0; i < size / KMSAN_ORIGIN_SIZE; i++)
		origin_start[i] = origin;
}

struct page *kmsan_vmalloc_to_page_or_null(void *vaddr)
{
	struct page *page;

	if (!kmsan_internal_is_vmalloc_addr(vaddr) &&
	    !kmsan_internal_is_module_addr(vaddr))
		return NULL;
	page = vmalloc_to_page(vaddr);
	if (pfn_valid(page_to_pfn(page)))
		return page;
	else
		return NULL;
}

void kmsan_internal_check_memory(void *addr, size_t size, const void *user_addr,
				 int reason)
{
	depot_stack_handle_t cur_origin = 0, new_origin = 0;
	unsigned long addr64 = (unsigned long)addr;
	depot_stack_handle_t *origin = NULL;
	unsigned char *shadow = NULL;
	int cur_off_start = -1;
	int chunk_size;
	size_t pos = 0;

	if (!size)
		return;
	KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(addr, size));
	while (pos < size) {
		chunk_size = min(size - pos,
				 PAGE_SIZE - ((addr64 + pos) % PAGE_SIZE));
		shadow = kmsan_get_metadata((void *)(addr64 + pos),
					    KMSAN_META_SHADOW);
		if (!shadow) {
			/*
			 * This page is untracked. If there were uninitialized
			 * bytes before, report them.
			 */
			if (cur_origin) {
				kmsan_enter_runtime();
				kmsan_report(cur_origin, addr, size,
					     cur_off_start, pos - 1, user_addr,
					     reason);
				kmsan_leave_runtime();
			}
			cur_origin = 0;
			cur_off_start = -1;
			pos += chunk_size;
			continue;
		}
		for (int i = 0; i < chunk_size; i++) {
			if (!shadow[i]) {
				/*
				 * This byte is unpoisoned. If there were
				 * poisoned bytes before, report them.
				 */
				if (cur_origin) {
					kmsan_enter_runtime();
					kmsan_report(cur_origin, addr, size,
						     cur_off_start, pos + i - 1,
						     user_addr, reason);
					kmsan_leave_runtime();
				}
				cur_origin = 0;
				cur_off_start = -1;
				continue;
			}
			origin = kmsan_get_metadata((void *)(addr64 + pos + i),
						    KMSAN_META_ORIGIN);
			KMSAN_WARN_ON(!origin);
			new_origin = *origin;
			/*
			 * Encountered new origin - report the previous
			 * uninitialized range.
			 */
			if (cur_origin != new_origin) {
				if (cur_origin) {
					kmsan_enter_runtime();
					kmsan_report(cur_origin, addr, size,
						     cur_off_start, pos + i - 1,
						     user_addr, reason);
					kmsan_leave_runtime();
				}
				cur_origin = new_origin;
				cur_off_start = pos + i;
			}
		}
		pos += chunk_size;
	}
	KMSAN_WARN_ON(pos != size);
	if (cur_origin) {
		kmsan_enter_runtime();
		kmsan_report(cur_origin, addr, size, cur_off_start, pos - 1,
			     user_addr, reason);
		kmsan_leave_runtime();
	}
}

bool kmsan_metadata_is_contiguous(void *addr, size_t size)
{
	char *cur_shadow = NULL, *next_shadow = NULL, *cur_origin = NULL,
	     *next_origin = NULL;
	u64 cur_addr = (u64)addr, next_addr = cur_addr + PAGE_SIZE;
	depot_stack_handle_t *origin_p;
	bool all_untracked = false;

	if (!size)
		return true;

	/* The whole range belongs to the same page. */
	if (ALIGN_DOWN(cur_addr + size - 1, PAGE_SIZE) ==
	    ALIGN_DOWN(cur_addr, PAGE_SIZE))
		return true;

	cur_shadow = kmsan_get_metadata((void *)cur_addr, /*is_origin*/ false);
	if (!cur_shadow)
		all_untracked = true;
	cur_origin = kmsan_get_metadata((void *)cur_addr, /*is_origin*/ true);
	if (all_untracked && cur_origin)
		goto report;

	for (; next_addr < (u64)addr + size;
	     cur_addr = next_addr, cur_shadow = next_shadow,
	     cur_origin = next_origin, next_addr += PAGE_SIZE) {
		next_shadow = kmsan_get_metadata((void *)next_addr, false);
		next_origin = kmsan_get_metadata((void *)next_addr, true);
		if (all_untracked) {
			if (next_shadow || next_origin)
				goto report;
			if (!next_shadow && !next_origin)
				continue;
		}
		if (((u64)cur_shadow == ((u64)next_shadow - PAGE_SIZE)) &&
		    ((u64)cur_origin == ((u64)next_origin - PAGE_SIZE)))
			continue;
		goto report;
	}
	return true;

report:
	pr_err("%s: attempting to access two shadow page ranges.\n", __func__);
	pr_err("Access of size %ld at %px.\n", size, addr);
	pr_err("Addresses belonging to different ranges: %px and %px\n",
	       (void *)cur_addr, (void *)next_addr);
	pr_err("page[0].shadow: %px, page[1].shadow: %px\n", cur_shadow,
	       next_shadow);
	pr_err("page[0].origin: %px, page[1].origin: %px\n", cur_origin,
	       next_origin);
	origin_p = kmsan_get_metadata(addr, KMSAN_META_ORIGIN);
	if (origin_p) {
		pr_err("Origin: %08x\n", *origin_p);
		kmsan_print_origin(*origin_p);
	} else {
		pr_err("Origin: unavailable\n");
	}
	return false;
}
Commit	Line	Data
f80be457 AP	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* KMSAN runtime library.
	4	*
	5	* Copyright (C) 2017-2022 Google LLC
	6	* Author: Alexander Potapenko <glider@google.com>
	7	*
	8	*/
	9
	10	#include <asm/page.h>
	11	#include <linux/compiler.h>
	12	#include <linux/export.h>
	13	#include <linux/highmem.h>
	14	#include <linux/interrupt.h>
	15	#include <linux/kernel.h>
	16	#include <linux/kmsan_types.h>
	17	#include <linux/memory.h>
	18	#include <linux/mm.h>
	19	#include <linux/mm_types.h>
	20	#include <linux/mmzone.h>
	21	#include <linux/percpu-defs.h>
	22	#include <linux/preempt.h>
	23	#include <linux/slab.h>
	24	#include <linux/stackdepot.h>
	25	#include <linux/stacktrace.h>
	26	#include <linux/types.h>
	27	#include <linux/vmalloc.h>
	28
	29	#include "../slab.h"
	30	#include "kmsan.h"
	31
	32	bool kmsan_enabled __read_mostly;
	33
	34	/*
	35	* Per-CPU KMSAN context to be used in interrupts, where current->kmsan is
	36	* unavaliable.
	37	*/
	38	DEFINE_PER_CPU(struct kmsan_ctx, kmsan_percpu_ctx);
	39
	40	void kmsan_internal_poison_memory(void *address, size_t size, gfp_t flags,
	41	unsigned int poison_flags)
	42	{
	43	u32 extra_bits =
	44	kmsan_extra_bits(/depth/ 0, poison_flags & KMSAN_POISON_FREE);
	45	bool checked = poison_flags & KMSAN_POISON_CHECK;
	46	depot_stack_handle_t handle;
	47
	48	handle = kmsan_save_stack_with_flags(flags, extra_bits);
	49	kmsan_internal_set_shadow_origin(address, size, -1, handle, checked);
	50	}
	51
	52	void kmsan_internal_unpoison_memory(void *address, size_t size, bool checked)
	53	{
	54	kmsan_internal_set_shadow_origin(address, size, 0, 0, checked);
	55	}
	56
	57	depot_stack_handle_t kmsan_save_stack_with_flags(gfp_t flags,
	58	unsigned int extra)
	59	{
	60	unsigned long entries[KMSAN_STACK_DEPTH];
	61	unsigned int nr_entries;
	62
	63	nr_entries = stack_trace_save(entries, KMSAN_STACK_DEPTH, 0);
	64
65	/* Don't sleep (see might_sleep_if() in __alloc_pages_nodemask()). */
66	flags &= ~__GFP_DIRECT_RECLAIM;
67
68	return __stack_depot_save(entries, nr_entries, extra, flags, true);
69	}
70
71	/* Copy the metadata following the memmove() behavior. */
72	void kmsan_internal_memmove_metadata(void dst, void src, size_t n)
73	{
74	depot_stack_handle_t old_origin = 0, new_origin = 0;
75	int src_slots, dst_slots, i, iter, step, skip_bits;
76	depot_stack_handle_t origin_src, origin_dst;
77	void shadow_src, shadow_dst;
78	u32 *align_shadow_src, shadow;
79	bool backwards;
80
81	shadow_dst = kmsan_get_metadata(dst, KMSAN_META_SHADOW);
82	if (!shadow_dst)
83	return;
84	KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(dst, n));
85
86	shadow_src = kmsan_get_metadata(src, KMSAN_META_SHADOW);
87	if (!shadow_src) {
88	/*
89	* @src is untracked: zero out destination shadow, ignore the
90	* origins, we're done.
91	*/
92	__memset(shadow_dst, 0, n);
93	return;
94	}
95	KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(src, n));
96
97	__memmove(shadow_dst, shadow_src, n);
98
99	origin_dst = kmsan_get_metadata(dst, KMSAN_META_ORIGIN);
100	origin_src = kmsan_get_metadata(src, KMSAN_META_ORIGIN);
101	KMSAN_WARN_ON(!origin_dst \|\| !origin_src);
102	src_slots = (ALIGN((u64)src + n, KMSAN_ORIGIN_SIZE) -
103	ALIGN_DOWN((u64)src, KMSAN_ORIGIN_SIZE)) /
104	KMSAN_ORIGIN_SIZE;
105	dst_slots = (ALIGN((u64)dst + n, KMSAN_ORIGIN_SIZE) -
106	ALIGN_DOWN((u64)dst, KMSAN_ORIGIN_SIZE)) /
107	KMSAN_ORIGIN_SIZE;
108	KMSAN_WARN_ON((src_slots < 1) \|\| (dst_slots < 1));
109	KMSAN_WARN_ON((src_slots - dst_slots > 1) \|\|
110	(dst_slots - src_slots < -1));
111
112	backwards = dst > src;
113	i = backwards ? min(src_slots, dst_slots) - 1 : 0;
114	iter = backwards ? -1 : 1;
115
116	align_shadow_src =
117	(u32 *)ALIGN_DOWN((u64)shadow_src, KMSAN_ORIGIN_SIZE);
118	for (step = 0; step < min(src_slots, dst_slots); step++, i += iter) {
119	KMSAN_WARN_ON(i < 0);
120	shadow = align_shadow_src[i];
121	if (i == 0) {
122	/*
123	* If @src isn't aligned on KMSAN_ORIGIN_SIZE, don't
124	* look at the first @src % KMSAN_ORIGIN_SIZE bytes
125	* of the first shadow slot.
126	*/
127	skip_bits = ((u64)src % KMSAN_ORIGIN_SIZE) * 8;
128	shadow = (shadow >> skip_bits) << skip_bits;
129	}
130	if (i == src_slots - 1) {
131	/*
132	* If @src + n isn't aligned on
133	* KMSAN_ORIGIN_SIZE, don't look at the last
134	* (@src + n) % KMSAN_ORIGIN_SIZE bytes of the
135	* last shadow slot.
136	*/
137	skip_bits = (((u64)src + n) % KMSAN_ORIGIN_SIZE) * 8;
138	shadow = (shadow << skip_bits) >> skip_bits;
139	}
140	/*
141	* Overwrite the origin only if the corresponding
142	* shadow is nonempty.
143	*/
144	if (origin_src[i] && (origin_src[i] != old_origin) && shadow) {
145	old_origin = origin_src[i];
146	new_origin = kmsan_internal_chain_origin(old_origin);
147	/*
148	* kmsan_internal_chain_origin() may return
149	* NULL, but we don't want to lose the previous
150	* origin value.
151	*/
152	if (!new_origin)
153	new_origin = old_origin;
154	}
155	if (shadow)
156	origin_dst[i] = new_origin;
157	else
158	origin_dst[i] = 0;
159	}
160	/*
161	* If dst_slots is greater than src_slots (i.e.
162	* dst_slots == src_slots + 1), there is an extra origin slot at the
163	* beginning or end of the destination buffer, for which we take the
164	* origin from the previous slot.
165	* This is only done if the part of the source shadow corresponding to
166	* slot is non-zero.
167	*
168	* E.g. if we copy 8 aligned bytes that are marked as uninitialized
169	* and have origins o111 and o222, to an unaligned buffer with offset 1,
170	* these two origins are copied to three origin slots, so one of then
171	* needs to be duplicated, depending on the copy direction (@backwards)
172	*
173	* src shadow: \|uuuu\|uuuu\|....\|
174	* src origin: \|o111\|o222\|....\|
175	*
176	* backwards = 0:
177	* dst shadow: \|.uuu\|uuuu\|u...\|
178	* dst origin: \|....\|o111\|o222\| - fill the empty slot with o111
179	* backwards = 1:
180	* dst shadow: \|.uuu\|uuuu\|u...\|
181	* dst origin: \|o111\|o222\|....\| - fill the empty slot with o222
182	*/
183	if (src_slots < dst_slots) {
184	if (backwards) {
185	shadow = align_shadow_src[src_slots - 1];
186	skip_bits = (((u64)dst + n) % KMSAN_ORIGIN_SIZE) * 8;
187	shadow = (shadow << skip_bits) >> skip_bits;
188	if (shadow)
189	/* src_slots > 0, therefore dst_slots is at least 2 */
190	origin_dst[dst_slots - 1] =
191	origin_dst[dst_slots - 2];
192	} else {
193	shadow = align_shadow_src[0];
194	skip_bits = ((u64)dst % KMSAN_ORIGIN_SIZE) * 8;
195	shadow = (shadow >> skip_bits) << skip_bits;
196	if (shadow)
197	origin_dst[0] = origin_dst[1];
198	}
199	}
200	}
201
202	depot_stack_handle_t kmsan_internal_chain_origin(depot_stack_handle_t id)
203	{
204	unsigned long entries[3];
205	u32 extra_bits;
206	int depth;
207	bool uaf;
208
209	if (!id)
210	return id;
211	/*
212	* Make sure we have enough spare bits in @id to hold the UAF bit and
213	* the chain depth.
214	*/
215	BUILD_BUG_ON(
216	(1 << STACK_DEPOT_EXTRA_BITS) <= (KMSAN_MAX_ORIGIN_DEPTH << 1));
217
218	extra_bits = stack_depot_get_extra_bits(id);
219	depth = kmsan_depth_from_eb(extra_bits);
220	uaf = kmsan_uaf_from_eb(extra_bits);
221
222	/*
223	* Stop chaining origins once the depth reached KMSAN_MAX_ORIGIN_DEPTH.
224	* This mostly happens in the case structures with uninitialized padding
225	* are copied around many times. Origin chains for such structures are
226	* usually periodic, and it does not make sense to fully store them.
227	*/
228	if (depth == KMSAN_MAX_ORIGIN_DEPTH)
229	return id;
230
231	depth++;
232	extra_bits = kmsan_extra_bits(depth, uaf);
233
234	entries[0] = KMSAN_CHAIN_MAGIC_ORIGIN;
235	entries[1] = kmsan_save_stack_with_flags(GFP_ATOMIC, 0);
236	entries[2] = id;
237	/*
238	* @entries is a local var in non-instrumented code, so KMSAN does not
239	* know it is initialized. Explicitly unpoison it to avoid false
240	* positives when __stack_depot_save() passes it to instrumented code.
241	*/
242	kmsan_internal_unpoison_memory(entries, sizeof(entries), false);
243	return __stack_depot_save(entries, ARRAY_SIZE(entries), extra_bits,
244	GFP_ATOMIC, true);
245	}
246
247	void kmsan_internal_set_shadow_origin(void *addr, size_t size, int b,
248	u32 origin, bool checked)
249	{
250	u64 address = (u64)addr;
251	void *shadow_start;
252	u32 *origin_start;
253	size_t pad = 0;
254
255	KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(addr, size));
256	shadow_start = kmsan_get_metadata(addr, KMSAN_META_SHADOW);
257	if (!shadow_start) {
258	/*
259	* kmsan_metadata_is_contiguous() is true, so either all shadow
260	* and origin pages are NULL, or all are non-NULL.
261	*/
262	if (checked) {
263	pr_err("%s: not memsetting %ld bytes starting at %px, because the shadow is NULL\n",
264	__func__, size, addr);
265	KMSAN_WARN_ON(true);
266	}
267	return;
268	}
269	__memset(shadow_start, b, size);
270
271	if (!IS_ALIGNED(address, KMSAN_ORIGIN_SIZE)) {
272	pad = address % KMSAN_ORIGIN_SIZE;
273	address -= pad;
274	size += pad;
275	}
276	size = ALIGN(size, KMSAN_ORIGIN_SIZE);
277	origin_start =
278	(u32 )kmsan_get_metadata((void )address, KMSAN_META_ORIGIN);
279
280	for (int i = 0; i < size / KMSAN_ORIGIN_SIZE; i++)
281	origin_start[i] = origin;
282	}
283
284	struct page kmsan_vmalloc_to_page_or_null(void vaddr)
285	{
286	struct page *page;
287
288	if (!kmsan_internal_is_vmalloc_addr(vaddr) &&
289	!kmsan_internal_is_module_addr(vaddr))
290	return NULL;
291	page = vmalloc_to_page(vaddr);
292	if (pfn_valid(page_to_pfn(page)))
293	return page;
294	else
295	return NULL;
296	}
297
298	void kmsan_internal_check_memory(void addr, size_t size, const void user_addr,
299	int reason)
300	{
301	depot_stack_handle_t cur_origin = 0, new_origin = 0;
302	unsigned long addr64 = (unsigned long)addr;
303	depot_stack_handle_t *origin = NULL;
304	unsigned char *shadow = NULL;
305	int cur_off_start = -1;
306	int chunk_size;
307	size_t pos = 0;
308
309	if (!size)
310	return;
311	KMSAN_WARN_ON(!kmsan_metadata_is_contiguous(addr, size));
312	while (pos < size) {
313	chunk_size = min(size - pos,
314	PAGE_SIZE - ((addr64 + pos) % PAGE_SIZE));
315	shadow = kmsan_get_metadata((void *)(addr64 + pos),
316	KMSAN_META_SHADOW);
317	if (!shadow) {
318	/*
319	* This page is untracked. If there were uninitialized
320	* bytes before, report them.
321	*/
322	if (cur_origin) {
323	kmsan_enter_runtime();
324	kmsan_report(cur_origin, addr, size,
325	cur_off_start, pos - 1, user_addr,
326	reason);
327	kmsan_leave_runtime();
328	}
329	cur_origin = 0;
330	cur_off_start = -1;
331	pos += chunk_size;
332	continue;
333	}
334	for (int i = 0; i < chunk_size; i++) {
335	if (!shadow[i]) {
336	/*
337	* This byte is unpoisoned. If there were
338	* poisoned bytes before, report them.
339	*/
340	if (cur_origin) {
341	kmsan_enter_runtime();
342	kmsan_report(cur_origin, addr, size,
343	cur_off_start, pos + i - 1,
344	user_addr, reason);
345	kmsan_leave_runtime();
346	}
347	cur_origin = 0;
348	cur_off_start = -1;
349	continue;
350	}
351	origin = kmsan_get_metadata((void *)(addr64 + pos + i),
352	KMSAN_META_ORIGIN);
353	KMSAN_WARN_ON(!origin);
354	new_origin = *origin;
355	/*
356	* Encountered new origin - report the previous
357	* uninitialized range.
358	*/
359	if (cur_origin != new_origin) {
360	if (cur_origin) {
361	kmsan_enter_runtime();
362	kmsan_report(cur_origin, addr, size,
363	cur_off_start, pos + i - 1,
364	user_addr, reason);
365	kmsan_leave_runtime();
366	}
367	cur_origin = new_origin;
368	cur_off_start = pos + i;
369	}
370	}
371	pos += chunk_size;
372	}
373	KMSAN_WARN_ON(pos != size);
374	if (cur_origin) {
375	kmsan_enter_runtime();
376	kmsan_report(cur_origin, addr, size, cur_off_start, pos - 1,
377	user_addr, reason);
378	kmsan_leave_runtime();
379	}
380	}
381
382	bool kmsan_metadata_is_contiguous(void *addr, size_t size)
383	{
384	char cur_shadow = NULL, next_shadow = NULL, *cur_origin = NULL,
385	*next_origin = NULL;
386	u64 cur_addr = (u64)addr, next_addr = cur_addr + PAGE_SIZE;
387	depot_stack_handle_t *origin_p;
388	bool all_untracked = false;
389
390	if (!size)
391	return true;
392
393	/* The whole range belongs to the same page. */
394	if (ALIGN_DOWN(cur_addr + size - 1, PAGE_SIZE) ==
395	ALIGN_DOWN(cur_addr, PAGE_SIZE))
396	return true;
397
398	cur_shadow = kmsan_get_metadata((void )cur_addr, /is_origin*/ false);
399	if (!cur_shadow)
400	all_untracked = true;
401	cur_origin = kmsan_get_metadata((void )cur_addr, /is_origin*/ true);
402	if (all_untracked && cur_origin)
403	goto report;
404
405	for (; next_addr < (u64)addr + size;
406	cur_addr = next_addr, cur_shadow = next_shadow,
407	cur_origin = next_origin, next_addr += PAGE_SIZE) {
408	next_shadow = kmsan_get_metadata((void *)next_addr, false);
409	next_origin = kmsan_get_metadata((void *)next_addr, true);
410	if (all_untracked) {
411	if (next_shadow \|\| next_origin)
412	goto report;
413	if (!next_shadow && !next_origin)
414	continue;
415	}
416	if (((u64)cur_shadow == ((u64)next_shadow - PAGE_SIZE)) &&
417	((u64)cur_origin == ((u64)next_origin - PAGE_SIZE)))
418	continue;
419	goto report;
420	}
421	return true;
422
423	report:
424	pr_err("%s: attempting to access two shadow page ranges.\n", __func__);
425	pr_err("Access of size %ld at %px.\n", size, addr);
426	pr_err("Addresses belonging to different ranges: %px and %px\n",
427	(void )cur_addr, (void )next_addr);
428	pr_err("page[0].shadow: %px, page[1].shadow: %px\n", cur_shadow,
429	next_shadow);
430	pr_err("page[0].origin: %px, page[1].origin: %px\n", cur_origin,
431	next_origin);
432	origin_p = kmsan_get_metadata(addr, KMSAN_META_ORIGIN);
433	if (origin_p) {
434	pr_err("Origin: %08x\n", *origin_p);
435	kmsan_print_origin(*origin_p);
436	} else {
437	pr_err("Origin: unavailable\n");
438	}
439	return false;
440	}