linux-kernel - [PATCH net] octeontx2-pf: Fix potential use after free in otx2_tc_add

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Message-ID: <aNKCL1jKwK8GRJHh@stanley.mountain>
Date: Tue, 23 Sep 2025 14:19:11 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Subbaraya Sundeep <sbhatta@...vell.com>
Cc: Sunil Goutham <sgoutham@...vell.com>,
	Geetha sowjanya <gakula@...vell.com>,
	hariprasad <hkelam@...vell.com>,
	Bharat Bhushan <bbhushan2@...vell.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH net] octeontx2-pf: Fix potential use after free in
 otx2_tc_add_flow()

This code calls kfree_rcu(new_node, rcu) and then dereferences "new_node"
and then dereferences it on the next line.  Two lines later, we take
a mutex so I don't think this is an RCU safe region.  Re-order it to do
the dereferences before queuing up the free.

Fixes: 68fbff68dbea ("octeontx2-pf: Add police action for TC flower")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c
index 5f80b23c5335..26a08d2cfbb1 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c
@@ -1326,7 +1326,6 @@ static int otx2_tc_add_flow(struct otx2_nic *nic,
 
 free_leaf:
 	otx2_tc_del_from_flow_list(flow_cfg, new_node);
-	kfree_rcu(new_node, rcu);
 	if (new_node->is_act_police) {
 		mutex_lock(&nic->mbox.lock);
 
@@ -1346,6 +1345,7 @@ static int otx2_tc_add_flow(struct otx2_nic *nic,
 
 		mutex_unlock(&nic->mbox.lock);
 	}
+	kfree_rcu(new_node, rcu);
 
 	return rc;
 }
-- 
2.51.0