shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-04 18:19:28 +09:00
Code Issues Packages Projects Releases Wiki Activity

cgroup: css_task_iter_skip()'d iterators must be advanced before accessed

Browse Source 
commit cee0c33c54 upstream.

b636fd38dc ("cgroup: Implement css_task_iter_skip()") introduced
css_task_iter_skip() which is used to fix task iterations skipping
dying threadgroup leaders with live threads.  Skipping is implemented
as a subportion of full advancing but css_task_iter_next() forgot to
fully advance a skipped iterator before determining the next task to
visit causing it to return invalid task pointers.

Fix it by making css_task_iter_next() fully advance the iterator if it
has been skipped since the previous iteration.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: syzbot
Link: http://lkml.kernel.org/r/00000000000097025d058a7fd785@google.com
Fixes: b636fd38dc ("cgroup: Implement css_task_iter_skip()")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo
2019-06-05 09:54:34 -07:00
committed by Greg Kroah-Hartman
parent feb6b123b7
commit ab348285f7
1 changed files with 4 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
kernel/cgroup/cgroup.c
View File

@@ -4197,6 +4197,10 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it)
spin_lock_irq(&css_set_lock);
/* @it may be half-advanced by skips, finish advancing */
if (it->flags & CSS_TASK_ITER_SKIPPED)
css_task_iter_advance(it);
if (it->task_pos) {
it->cur_task = list_entry(it->task_pos, struct task_struct,
cg_list);