diff options
author | Tejun Heo <tj@kernel.org> | 2019-06-05 09:54:34 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-08-09 17:53:36 +0200 |
commit | ab348285f70438d1fd468e1ffb695cd671124a00 (patch) | |
tree | 2f7a1f3130168aa94635d5bf0eda9d3c95156d4d /kernel/cgroup | |
parent | feb6b123b7ddfa381f6ea8c04ea8a305416c4b8e (diff) |
cgroup: css_task_iter_skip()'d iterators must be advanced before accessed
commit cee0c33c546a93957a52ae9ab6bebadbee765ec5 upstream.
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()")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/cgroup')
-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 8eb37e732253..2fb283f689a4 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -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); |