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linux-next/drivers/cpufreq/cpufreq_governor_attr_set.c
James Morse cdef119660 cpufreq: schedutil: Destroy mutex before kobject_put() frees the memory
Since commit e5c6b312ce ("cpufreq: schedutil: Use kobject release()
method to free sugov_tunables") kobject_put() has kfree()d the
attr_set before gov_attr_set_put() returns.

kobject_put() isn't the last user of attr_set in gov_attr_set_put(),
the subsequent mutex_destroy() triggers a use-after-free:
| BUG: KASAN: use-after-free in mutex_is_locked+0x20/0x60
| Read of size 8 at addr ffff000800ca4250 by task cpuhp/2/20
|
| CPU: 2 PID: 20 Comm: cpuhp/2 Not tainted 5.15.0-rc1 #12369
| Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development
| Platform, BIOS EDK II Jul 30 2018
| Call trace:
|  dump_backtrace+0x0/0x380
|  show_stack+0x1c/0x30
|  dump_stack_lvl+0x8c/0xb8
|  print_address_description.constprop.0+0x74/0x2b8
|  kasan_report+0x1f4/0x210
|  kasan_check_range+0xfc/0x1a4
|  __kasan_check_read+0x38/0x60
|  mutex_is_locked+0x20/0x60
|  mutex_destroy+0x80/0x100
|  gov_attr_set_put+0xfc/0x150
|  sugov_exit+0x78/0x190
|  cpufreq_offline.isra.0+0x2c0/0x660
|  cpuhp_cpufreq_offline+0x14/0x24
|  cpuhp_invoke_callback+0x430/0x6d0
|  cpuhp_thread_fun+0x1b0/0x624
|  smpboot_thread_fn+0x5e0/0xa6c
|  kthread+0x3a0/0x450
|  ret_from_fork+0x10/0x20

Swap the order of the calls.

Fixes: e5c6b312ce ("cpufreq: schedutil: Use kobject release() method to free sugov_tunables")
Cc: 4.7+ <stable@vger.kernel.org> # 4.7+
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2021-09-14 19:01:36 +02:00

82 lines
2.1 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Abstract code for CPUFreq governor tunable sysfs attributes.
*
* Copyright (C) 2016, Intel Corporation
* Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
*/
#include "cpufreq_governor.h"
static inline struct gov_attr_set *to_gov_attr_set(struct kobject *kobj)
{
return container_of(kobj, struct gov_attr_set, kobj);
}
static inline struct governor_attr *to_gov_attr(struct attribute *attr)
{
return container_of(attr, struct governor_attr, attr);
}
static ssize_t governor_show(struct kobject *kobj, struct attribute *attr,
char *buf)
{
struct governor_attr *gattr = to_gov_attr(attr);
return gattr->show(to_gov_attr_set(kobj), buf);
}
static ssize_t governor_store(struct kobject *kobj, struct attribute *attr,
const char *buf, size_t count)
{
struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
struct governor_attr *gattr = to_gov_attr(attr);
int ret;
mutex_lock(&attr_set->update_lock);
ret = attr_set->usage_count ? gattr->store(attr_set, buf, count) : -EBUSY;
mutex_unlock(&attr_set->update_lock);
return ret;
}
const struct sysfs_ops governor_sysfs_ops = {
.show = governor_show,
.store = governor_store,
};
EXPORT_SYMBOL_GPL(governor_sysfs_ops);
void gov_attr_set_init(struct gov_attr_set *attr_set, struct list_head *list_node)
{
INIT_LIST_HEAD(&attr_set->policy_list);
mutex_init(&attr_set->update_lock);
attr_set->usage_count = 1;
list_add(list_node, &attr_set->policy_list);
}
EXPORT_SYMBOL_GPL(gov_attr_set_init);
void gov_attr_set_get(struct gov_attr_set *attr_set, struct list_head *list_node)
{
mutex_lock(&attr_set->update_lock);
attr_set->usage_count++;
list_add(list_node, &attr_set->policy_list);
mutex_unlock(&attr_set->update_lock);
}
EXPORT_SYMBOL_GPL(gov_attr_set_get);
unsigned int gov_attr_set_put(struct gov_attr_set *attr_set, struct list_head *list_node)
{
unsigned int count;
mutex_lock(&attr_set->update_lock);
list_del(list_node);
count = --attr_set->usage_count;
mutex_unlock(&attr_set->update_lock);
if (count)
return count;
mutex_destroy(&attr_set->update_lock);
kobject_put(&attr_set->kobj);
return 0;
}
EXPORT_SYMBOL_GPL(gov_attr_set_put);