linux-kernel - [PATCH] cpufreq: Init completion before kobject_init_and

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Date:   Thu, 10 Nov 2022 14:23:07 +0000
From:   Yongqiang Liu <liuyongqiang13@...wei.com>
To:     <rafael@...nel.org>, <viresh.kumar@...aro.org>, <tobin@...nel.org>
CC:     <zhangxiaoxu5@...wei.com>, <linux-pm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] cpufreq: Init completion before kobject_init_and_add()

In cpufreq_policy_alloc(), it will call uninitialed completion in
cpufreq_sysfs_release() when kobject_init_and_add() fails. And
that will cause a crash such as the following page fault in complete:

BUG: unable to handle page fault for address: fffffffffffffff8
[..]
RIP: 0010:complete+0x98/0x1f0
[..]
Call Trace:
 kobject_put+0x1be/0x4c0
 cpufreq_online.cold+0xee/0x1fd
 cpufreq_add_dev+0x183/0x1e0
 subsys_interface_register+0x3f5/0x4e0
 cpufreq_register_driver+0x3b7/0x670
 acpi_cpufreq_init+0x56c/0x1000 [acpi_cpufreq]
 do_one_initcall+0x13d/0x780
 do_init_module+0x1c3/0x630
 load_module+0x6e67/0x73b0
 __do_sys_finit_module+0x181/0x240
 do_syscall_64+0x35/0x80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: 4ebe36c94aed ("cpufreq: Fix kobject memleak")
Signed-off-by: Yongqiang Liu <liuyongqiang13@...wei.com>
---
 drivers/cpufreq/cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 69b3d61852ac..7e56a42750ea 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1207,6 +1207,7 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
 	if (!zalloc_cpumask_var(&policy->real_cpus, GFP_KERNEL))
 		goto err_free_rcpumask;
 
+	init_completion(&policy->kobj_unregister);
 	ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
 				   cpufreq_global_kobject, "policy%u", cpu);
 	if (ret) {
@@ -1245,7 +1246,6 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
 	init_rwsem(&policy->rwsem);
 	spin_lock_init(&policy->transition_lock);
 	init_waitqueue_head(&policy->transition_wait);
-	init_completion(&policy->kobj_unregister);
 	INIT_WORK(&policy->update, handle_update);
 
 	policy->cpu = cpu;
-- 
2.25.1