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Linux kernel source tree
6f363f5aa8
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 <cuigaosheng1@huawei.com>
Link: https://www.spinics.net/lists/cgroups/msg37935.html
Suggested-by: Michal Koutný <mkoutny@suse.com>
Link: https://lore.kernel.org/all/20230526114139.70274-1-xiujianfeng@huaweicloud.com/
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.