mm/kasan/tags.c

// SPDX-License-Identifier: GPL-2.0
/*
 * This file contains common tag-based KASAN code.
 *
 * Copyright (c) 2018 Google, Inc.
 * Copyright (c) 2020 Google, Inc.
 */

#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/memory.h>
#include <linux/mm.h>
#include <linux/static_key.h>
#include <linux/string.h>
#include <linux/types.h>

#include "kasan.h"

void kasan_set_free_info(struct kmem_cache *cache,
				void *object, u8 tag)
{
	struct kasan_alloc_meta *alloc_meta;
	u8 idx = 0;

	alloc_meta = kasan_get_alloc_meta(cache, object);
	if (!alloc_meta)
		return;

#ifdef CONFIG_KASAN_TAGS_IDENTIFY
	idx = alloc_meta->free_track_idx;
	alloc_meta->free_pointer_tag[idx] = tag;
	alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS;
#endif

	kasan_set_track(&alloc_meta->free_track[idx], GFP_NOWAIT);
}

struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
				void *object, u8 tag)
{
	struct kasan_alloc_meta *alloc_meta;
	int i = 0;

	alloc_meta = kasan_get_alloc_meta(cache, object);
	if (!alloc_meta)
		return NULL;

#ifdef CONFIG_KASAN_TAGS_IDENTIFY
	for (i = 0; i < KASAN_NR_FREE_STACKS; i++) {
		if (alloc_meta->free_pointer_tag[i] == tag)
			break;
	}
	if (i == KASAN_NR_FREE_STACKS)
		i = alloc_meta->free_track_idx;
#endif

	return &alloc_meta->free_track[i];
}