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authorPaul E. McKenney <paulmck@kernel.org>2021-05-25 10:12:45 -0700
committerPaul E. McKenney <paulmck@kernel.org>2021-07-06 12:38:21 -0700
commit1d10bf55d85d34eb73dd8263635f43fd72135d2d (patch)
tree098a4e33b5347ac9c22257dc313f2b5528c982e6 /kernel/rcu
parent05bc276cf243d90b9f1eb6ae2962f41eeb53a741 (diff)
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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>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tasks.h5
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!!!