diff options
| author | Tejun Heo <tj@kernel.org> | 2019-06-05 09:54:34 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2019-06-05 09:54:34 -0700 |
| commit | cee0c33c546a93957a52ae9ab6bebadbee765ec5 (patch) | |
| tree | 677530356898bb2d9b4633f2a39065788ff2a619 /kernel | |
| parent | c03cd7738a83b13739f00546166969342c8ff014 (diff) | |
cgroup: css_task_iter_skip()'d iterators must be advanced before accessed
b636fd38dc40 ("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: b636fd38dc40 ("cgroup: Implement css_task_iter_skip()")
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/cgroup.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index a7df319c2e9a..9538a12d42d6 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4550,6 +4550,10 @@ 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); |