From: Paul E. McKenney <paulmck@xxxxxxxxxx>
[ Upstream commit 8ed00760203d8018bee042fbfe8e076579be2c2b ]
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: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/rcu/srcutree.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 6833d8887181..d30e4db04506 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -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);
--
2.35.1
