diff options
| author | Paul E. McKenney | 2021-05-25 10:12:45 -0700 |
|---|---|---|
| committer | Paul E. McKenney | 2021-07-06 12:38:21 -0700 |
| commit | 1d10bf55d85d34eb73dd8263635f43fd72135d2d (patch) | |
| tree | 098a4e33b5347ac9c22257dc313f2b5528c982e6 | |
| parent | 05bc276cf243d90b9f1eb6ae2962f41eeb53a741 (diff) | |
rcu-tasks: Don't delete holdouts within trc_inspect_reader()
As Yanfei pointed out, although invoking trc_del_holdout() is safe
from the viewpoint of the integrity of the holdout list itself,
the put_task_struct() invoked by trc_del_holdout() can result in
use-after-free errors due to later accesses to this task_struct structure
by the RCU Tasks Trace grace-period kthread.
This commit therefore removes this call to trc_del_holdout() from
trc_inspect_reader() in favor of the grace-period thread's existing call
to trc_del_holdout(), thus eliminating that particular class of
use-after-free errors.
Reported-by: "Xu, Yanfei" <yanfei.xu@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| -rw-r--r-- | kernel/rcu/tasks.h | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 03a118d1c003..3d5cb6cb8a6d 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -953,10 +953,9 @@ static bool trc_inspect_reader(struct task_struct *t, void *arg) in_qs = likely(!t->trc_reader_nesting); } - // Mark as checked. Because this is called from the grace-period - // kthread, also remove the task from the holdout list. + // Mark as checked so that the grace-period kthread will + // remove it from the holdout list. t->trc_reader_checked = true; - trc_del_holdout(t); if (in_qs) return true; // Already in quiescent state, done!!! |