[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20250507112605.20910-3-qiang.zhang1211@gmail.com>
Date: Wed, 7 May 2025 19:26:05 +0800
From: Zqiang <qiang.zhang1211@...il.com>
To: paulmck@...nel.org,
frederic@...nel.org,
neeraj.upadhyay@...nel.org,
joel@...lfernandes.org,
urezki@...il.com,
boqun.feng@...il.com
Cc: qiang.zhang1211@...il.com,
rcu@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH] rcu/nocb: Fix possible invalid rdp's->nocb_cb_kthread pointer access
In the preparation stage of CPU online, if the corresponding
the rdp's->nocb_cb_kthread does not exist, will be created,
there is a situation where the rdp's rcuop kthreads creation fails,
and then de-offload this CPU's rdp, does not assign this CPU's
rdp->nocb_cb_kthread pointer, but this rdp's->nocb_gp_rdp and
rdp's->rdp_gp->nocb_gp_kthread is still valid.
This will cause the subsequent re-offload operation of this offline
CPU, which will pass the conditional check and the kthread_unpark()
will access invalid rdp's->nocb_cb_kthread pointer.
This commit therefore use rdp's->nocb_gp_kthread instead of
rdp_gp's->nocb_gp_kthread for safety check.
Signed-off-by: Zqiang <qiang.zhang1211@...il.com>
---
kernel/rcu/tree_nocb.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
index 1596812f7f12..6679140bb0b5 100644
--- a/kernel/rcu/tree_nocb.h
+++ b/kernel/rcu/tree_nocb.h
@@ -1146,7 +1146,6 @@ static bool rcu_nocb_rdp_offload_wait_cond(struct rcu_data *rdp)
static int rcu_nocb_rdp_offload(struct rcu_data *rdp)
{
int wake_gp;
- struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
WARN_ON_ONCE(cpu_online(rdp->cpu));
/*
@@ -1156,7 +1155,7 @@ static int rcu_nocb_rdp_offload(struct rcu_data *rdp)
if (!rdp->nocb_gp_rdp)
return -EINVAL;
- if (WARN_ON_ONCE(!rdp_gp->nocb_gp_kthread))
+ if (WARN_ON_ONCE(!rdp->nocb_gp_kthread))
return -EINVAL;
pr_info("Offloading %d\n", rdp->cpu);
@@ -1166,7 +1165,7 @@ static int rcu_nocb_rdp_offload(struct rcu_data *rdp)
wake_gp = rcu_nocb_queue_toggle_rdp(rdp);
if (wake_gp)
- wake_up_process(rdp_gp->nocb_gp_kthread);
+ wake_up_process(rdp->nocb_gp_kthread);
swait_event_exclusive(rdp->nocb_state_wq,
rcu_nocb_rdp_offload_wait_cond(rdp));
--
2.17.1
Powered by blists - more mailing lists