user/sven/linux.git/kernel/cgroup, branch v5.4.298

cgroup: Fix compilation issue due to cgroup_mutex not being exported

2025-06-04T12:32:29Z

[ Upstream commit 87c259a7a359e73e6c52c68fcbec79988999b4e6 ] When adding folio_memcg function call in the zram module for Android16-6.12, the following error occurs during compilation: ERROR: modpost: "cgroup_mutex" [../soc-repo/zram.ko] undefined! This error is caused by the indirect call to lockdep_is_held(&cgroup_mutex) within folio_memcg. The export setting for cgroup_mutex is controlled by the CONFIG_PROVE_RCU macro. If CONFIG_LOCKDEP is enabled while CONFIG_PROVE_RCU is not, this compilation error will occur. To resolve this issue, add a parallel macro CONFIG_LOCKDEP control to ensure cgroup_mutex is properly exported when needed. Signed-off-by: gao xu Acked-by: Michal Koutný Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cgroup: Make operations on the cgroup root_list RCU safe

2024-12-14T18:44:35Z

commit d23b5c577715892c87533b13923306acc6243f93 upstream. At present, when we perform operations on the cgroup root_list, we must hold the cgroup_mutex, which is a relatively heavyweight lock. In reality, we can make operations on this list RCU-safe, eliminating the need to hold the cgroup_mutex during traversal. Modifications to the list only occur in the cgroup root setup and destroy paths, which should be infrequent in a production environment. In contrast, traversal may occur frequently. Therefore, making it RCU-safe would be beneficial. Signed-off-by: Yafang Shao Signed-off-by: Tejun Heo [fp: adapt to 5.10 mainly because of changes made by e210a89f5b07 ("cgroup.c: add helper __cset_cgroup_from_root to cleanup duplicated codes")] Signed-off-by: Fedor Pchelkin [Shivani: Modified to apply on v5.4.y] Signed-off-by: Shivani Agarwal Reviewed-by: Siddh Raman Pant Signed-off-by: Siddh Raman Pant Signed-off-by: Greg Kroah-Hartman

cgroup: Fix potential overflow issue when checking max_depth

2024-11-08T15:20:52Z

[ Upstream commit 3cc4e13bb1617f6a13e5e6882465984148743cf4 ] cgroup.max.depth is the maximum allowed descent depth below the current cgroup. If the actual descent depth is equal or larger, an attempt to create a new child cgroup will fail. However due to the cgroup->max_depth is of int type and having the default value INT_MAX, the condition 'level > cgroup->max_depth' will never be satisfied, and it will cause an overflow of the level after it reaches to INT_MAX. Fix it by starting the level from 0 and using '>=' instead. It's worth mentioning that this issue is unlikely to occur in reality, as it's impossible to have a depth of INT_MAX hierarchy, but should be be avoided logically. Fixes: 1a926e0bbab8 ("cgroup: implement hierarchy limits") Signed-off-by: Xiu Jianfeng Reviewed-by: Michal Koutný Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cgroup: Protect css->cgroup write under css_set_lock

2024-09-12T09:03:53Z

[ Upstream commit 57b56d16800e8961278ecff0dc755d46c4575092 ] The writing of css->cgroup associated with the cgroup root in rebind_subsystems() is currently protected only by cgroup_mutex. However, the reading of css->cgroup in both proc_cpuset_show() and proc_cgroup_show() is protected just by css_set_lock. That makes the readers susceptible to racing problems like data tearing or caching. It is also a problem that can be reported by KCSAN. This can be fixed by using READ_ONCE() and WRITE_ONCE() to access css->cgroup. Alternatively, the writing of css->cgroup can be moved under css_set_lock as well which is done by this patch. Signed-off-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cgroup/cpuset: Prevent UAF in proc_cpuset_show()

2024-09-04T11:15:03Z

commit 1be59c97c83ccd67a519d8a49486b3a8a73ca28a upstream. An UAF can happen when /proc/cpuset is read as reported in [1]. This can be reproduced by the following methods: 1.add an mdelay(1000) before acquiring the cgroup_lock In the cgroup_path_ns function. 2.$cat /proc//cpuset repeatly. 3.$mount -t cgroup -o cpuset cpuset /sys/fs/cgroup/cpuset/ $umount /sys/fs/cgroup/cpuset/ repeatly. The race that cause this bug can be shown as below: (umount) | (cat /proc//cpuset) css_release | proc_cpuset_show css_release_work_fn | css = task_get_css(tsk, cpuset_cgrp_id); css_free_rwork_fn | cgroup_path_ns(css->cgroup, ...); cgroup_destroy_root | mutex_lock(&cgroup_mutex); rebind_subsystems | cgroup_free_root | | // cgrp was freed, UAF | cgroup_path_ns_locked(cgrp,..); When the cpuset is initialized, the root node top_cpuset.css.cgrp will point to &cgrp_dfl_root.cgrp. In cgroup v1, the mount operation will allocate cgroup_root, and top_cpuset.css.cgrp will point to the allocated &cgroup_root.cgrp. When the umount operation is executed, top_cpuset.css.cgrp will be rebound to &cgrp_dfl_root.cgrp. The problem is that when rebinding to cgrp_dfl_root, there are cases where the cgroup_root allocated by setting up the root for cgroup v1 is cached. This could lead to a Use-After-Free (UAF) if it is subsequently freed. The descendant cgroups of cgroup v1 can only be freed after the css is released. However, the css of the root will never be released, yet the cgroup_root should be freed when it is unmounted. This means that obtaining a reference to the css of the root does not guarantee that css.cgrp->root will not be freed. Fix this problem by using rcu_read_lock in proc_cpuset_show(). As cgroup_root is kfree_rcu after commit d23b5c577715 ("cgroup: Make operations on the cgroup root_list RCU safe"), css->cgroup won't be freed during the critical section. To call cgroup_path_ns_locked, css_set_lock is needed, so it is safe to replace task_get_css with task_css. [1] https://syzkaller.appspot.com/bug?extid=9b1ff7be974a403aa4cd Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces") Signed-off-by: Chen Ridong Signed-off-by: Tejun Heo Signed-off-by: Shivani Agarwal Signed-off-by: Greg Kroah-Hartman

sched/fair: Allow disabling sched_balance_newidle with sched_relax_domain_level

2024-06-16T11:28:41Z

[ Upstream commit a1fd0b9d751f840df23ef0e75b691fc00cfd4743 ] Change relax_domain_level checks so that it would be possible to include or exclude all domains from newidle balancing. This matches the behavior described in the documentation: -1 no request. use system default or follow request of others. 0 no search. 1 search siblings (hyperthreads in a core). "2" enables levels 0 and 1, level_max excludes the last (level_max) level, and level_max+1 includes all levels. Fixes: 1d3504fcf560 ("sched, cpuset: customize sched domains, core") Signed-off-by: Vitalii Bursov Signed-off-by: Ingo Molnar Tested-by: Dietmar Eggemann Reviewed-by: Vincent Guittot Reviewed-by: Valentin Schneider Link: https://lore.kernel.org/r/bd6de28e80073c79466ec6401cdeae78f0d4423d.1714488502.git.vitaly@bursov.com Signed-off-by: Sasha Levin

cgroup: Remove duplicates in cgroup v1 tasks file

2023-10-25T09:53:19Z

commit 1ca0b605150501b7dc59f3016271da4eb3e96fce upstream. One PID may appear multiple times in a preloaded pidlist. (Possibly due to PID recycling but we have reports of the same task_struct appearing with different PIDs, thus possibly involving transfer of PID via de_thread().) Because v1 seq_file iterator uses PIDs as position, it leads to a message: > seq_file: buggy .next function kernfs_seq_next did not update position index Conservative and quick fix consists of removing duplicates from `tasks` file (as opposed to removing pidlists altogether). It doesn't affect correctness (it's sufficient to show a PID once), performance impact would be hidden by unconditional sorting of the pidlist already in place (asymptotically). Link: https://lore.kernel.org/r/20230823174804.23632-1-mkoutny@suse.com/ Suggested-by: Firo Yang Signed-off-by: Michal Koutný Signed-off-by: Tejun Heo Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

cgroup: Do not corrupt task iteration when rebinding subsystem

2023-06-28T08:18:36Z

commit 6f363f5aa845561f7ea496d8b1175e3204470486 upstream. We found a refcount UAF bug as follows: refcount_t: addition on 0; use-after-free. WARNING: CPU: 1 PID: 342 at lib/refcount.c:25 refcount_warn_saturate+0xa0/0x148 Workqueue: events cpuset_hotplug_workfn Call trace: refcount_warn_saturate+0xa0/0x148 __refcount_add.constprop.0+0x5c/0x80 css_task_iter_advance_css_set+0xd8/0x210 css_task_iter_advance+0xa8/0x120 css_task_iter_next+0x94/0x158 update_tasks_root_domain+0x58/0x98 rebuild_root_domains+0xa0/0x1b0 rebuild_sched_domains_locked+0x144/0x188 cpuset_hotplug_workfn+0x138/0x5a0 process_one_work+0x1e8/0x448 worker_thread+0x228/0x3e0 kthread+0xe0/0xf0 ret_from_fork+0x10/0x20 then a kernel panic will be triggered as below: Unable to handle kernel paging request at virtual address 00000000c0000010 Call trace: cgroup_apply_control_disable+0xa4/0x16c rebind_subsystems+0x224/0x590 cgroup_destroy_root+0x64/0x2e0 css_free_rwork_fn+0x198/0x2a0 process_one_work+0x1d4/0x4bc worker_thread+0x158/0x410 kthread+0x108/0x13c ret_from_fork+0x10/0x18 The race that cause this bug can be shown as below: (hotplug cpu) | (umount cpuset) mutex_lock(&cpuset_mutex) | mutex_lock(&cgroup_mutex) cpuset_hotplug_workfn | rebuild_root_domains | rebind_subsystems update_tasks_root_domain | spin_lock_irq(&css_set_lock) css_task_iter_start | list_move_tail(&cset->e_cset_node[ss->id] while(css_task_iter_next) | &dcgrp->e_csets[ss->id]); css_task_iter_end | spin_unlock_irq(&css_set_lock) mutex_unlock(&cpuset_mutex) | mutex_unlock(&cgroup_mutex) Inside css_task_iter_start/next/end, css_set_lock is hold and then released, so when iterating task(left side), the css_set may be moved to another list(right side), then it->cset_head points to the old list head and it->cset_pos->next points to the head node of new list, which can't be used as struct css_set. To fix this issue, switch from all css_sets to only scgrp's css_sets to patch in-flight iterators to preserve correct iteration, and then update it->cset_head as well. Reported-by: Gaosheng Cui Link: https://www.spinics.net/lists/cgroups/msg37935.html Suggested-by: Michal Koutný Link: https://lore.kernel.org/all/20230526114139.70274-1-xiujianfeng@huaweicloud.com/ Signed-off-by: Xiu Jianfeng Fixes: 2d8f243a5e6e ("cgroup: implement cgroup->e_csets[]") Cc: stable@vger.kernel.org # v3.16+ Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

cgroup/cpuset: Wake up cpuset_attach_wq tasks in cpuset_cancel_attach()

2023-04-20T10:07:32Z

commit ba9182a89626d5f83c2ee4594f55cb9c1e60f0e2 upstream. After a successful cpuset_can_attach() call which increments the attach_in_progress flag, either cpuset_cancel_attach() or cpuset_attach() will be called later. In cpuset_attach(), tasks in cpuset_attach_wq, if present, will be woken up at the end. That is not the case in cpuset_cancel_attach(). So missed wakeup is possible if the attach operation is somehow cancelled. Fix that by doing the wakeup in cpuset_cancel_attach() as well. Fixes: e44193d39e8d ("cpuset: let hotplug propagation work wait for task attaching") Signed-off-by: Waiman Long Reviewed-by: Michal Koutný Cc: stable@vger.kernel.org # v3.11+ Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

memcg: fix possible use-after-free in memcg_write_event_control()

2022-12-14T10:30:43Z

commit 4a7ba45b1a435e7097ca0f79a847d0949d0eb088 upstream. memcg_write_event_control() accesses the dentry->d_name of the specified control fd to route the write call. As a cgroup interface file can't be renamed, it's safe to access d_name as long as the specified file is a regular cgroup file. Also, as these cgroup interface files can't be removed before the directory, it's safe to access the parent too. Prior to 347c4a874710 ("memcg: remove cgroup_event->cft"), there was a call to __file_cft() which verified that the specified file is a regular cgroupfs file before further accesses. The cftype pointer returned from __file_cft() was no longer necessary and the commit inadvertently dropped the file type check with it allowing any file to slip through. With the invarients broken, the d_name and parent accesses can now race against renames and removals of arbitrary files and cause use-after-free's. Fix the bug by resurrecting the file type check in __file_cft(). Now that cgroupfs is implemented through kernfs, checking the file operations needs to go through a layer of indirection. Instead, let's check the superblock and dentry type. Link: https://lkml.kernel.org/r/Y5FRm/cfcKPGzWwl@slm.duckdns.org Fixes: 347c4a874710 ("memcg: remove cgroup_event->cft") Signed-off-by: Tejun Heo Reported-by: Jann Horn Acked-by: Roman Gushchin Acked-by: Johannes Weiner Cc: Linus Torvalds Cc: Michal Hocko Cc: Muchun Song Cc: Shakeel Butt Cc: [3.14+] Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman