Commit 8ed00760 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

srcu: Tighten cleanup_srcu_struct() GP checks 



Currently, cleanup_srcu_struct() checks for a grace period in progress,
but it does not check for a grace period that has not yet started but
which might start at any time.  Such a situation could result in a
use-after-free bug, so this commit adds a check for a grace period that
is needed but not yet started to cleanup_srcu_struct().

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 31231092

kernel/rcu/srcutree.c

+4 −2
Original line number Diff line number Diff line
@@ -382,9 +382,11 @@ void cleanup_srcu_struct(struct srcu_struct *ssp) 
			return; /* Forgot srcu_barrier(), so just leak it! */

	}

	if (WARN_ON(rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) != SRCU_STATE_IDLE) ||

	    WARN_ON(rcu_seq_current(&ssp->srcu_gp_seq) != ssp->srcu_gp_seq_needed) ||

	    WARN_ON(srcu_readers_active(ssp))) {

		pr_info("%s: Active srcu_struct %p state: %d\n",

			__func__, ssp, rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)));

		pr_info("%s: Active srcu_struct %p read state: %d gp state: %lu/%lu\n",

			__func__, ssp, rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)),

			rcu_seq_current(&ssp->srcu_gp_seq), ssp->srcu_gp_seq_needed);

		return; /* Caller forgot to stop doing call_srcu()? */

	}

	free_percpu(ssp->sda);