Commit c2d83556 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Yongqiang Liu
Browse files

cgroup: Add missing cpus_read_lock() to cgroup_attach_task_all() 

mainline inclusion
from mainline-v6.0-rc3
commit 43626dad
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6L46J
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=43626dade36fa74d3329046f4ae2d7fdefe401c6

--------------------------------

syzbot is hitting percpu_rwsem_assert_held(&cpu_hotplug_lock) warning at
cpuset_attach() [1], for commit 4f7e7236 ("cgroup: Fix
threadgroup_rwsem <-> cpus_read_lock() deadlock") missed that
cpuset_attach() is also called from cgroup_attach_task_all().
Add cpus_read_lock() like what cgroup_procs_write_start() does.

Link: https://syzkaller.appspot.com/bug?extid=29d3a3b4d86c8136ad9e

 [1]
Reported-by: default avatarsyzbot <syzbot+29d3a3b4d86c8136ad9e@syzkaller.appspotmail.com>
Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Fixes: 4f7e7236 ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock")
Signed-off-by: default avatarTejun Heo <tj@kernel.org>

conflicts:
	kernel/cgroup/cgroup-internal.h
	kernel/cgroup/cgroup-v1.c
	kernel/cgroup/cgroup.c

Signed-off-by: default avatarCai Xinchen <caixinchen1@huawei.com>
Reviewed-by: default avatarWang Weiyang <wangweiyang2@huawei.com>
Reviewed-by: default avatarXiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: default avatarWang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: default avatarYongqiang Liu <liuyongqiang13@huawei.com>
parent 4924308a

kernel/cgroup/cgroup-internal.h

+2 −0
Original line number Diff line number Diff line
@@ -226,6 +226,8 @@ int cgroup_migrate(struct task_struct *leader, bool threadgroup, 


int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,

		       bool threadgroup);

void cgroup_attach_lock(void);

void cgroup_attach_unlock(void);

struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)

	__acquires(&cgroup_threadgroup_rwsem);

void cgroup_procs_write_finish(struct task_struct *task)

kernel/cgroup/cgroup-v1.c

+2 −2
Original line number Diff line number Diff line
@@ -55,7 +55,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) 
	int retval = 0;



	mutex_lock(&cgroup_mutex);

	percpu_down_write(&cgroup_threadgroup_rwsem);

	cgroup_attach_lock();

	for_each_root(root) {

		struct cgroup *from_cgrp;
@@ -70,7 +70,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) 
		if (retval)

			break;

	}

	percpu_up_write(&cgroup_threadgroup_rwsem);

	cgroup_attach_unlock();

	mutex_unlock(&cgroup_mutex);



	return retval;

kernel/cgroup/cgroup.c

+2 −2
Original line number Diff line number Diff line
@@ -2236,7 +2236,7 @@ EXPORT_SYMBOL_GPL(task_cgroup_path); 
 * write-locking cgroup_threadgroup_rwsem. This allows ->attach() to assume that

 * CPU hotplug is disabled on entry.

 */

static void cgroup_attach_lock(void)

void cgroup_attach_lock(void)

{

	cpus_read_lock();

	percpu_down_write(&cgroup_threadgroup_rwsem);
@@ -2246,7 +2246,7 @@ static void cgroup_attach_lock(void) 
 * cgroup_attach_unlock - Undo cgroup_attach_lock()

 * @lock_threadgroup: whether to up_write cgroup_threadgroup_rwsem

 */

static void cgroup_attach_unlock(void)

void cgroup_attach_unlock(void)

{

	percpu_up_write(&cgroup_threadgroup_rwsem);

	cpus_read_unlock();