linux-kernel - [PATCH v5.15-v6.1 2/2] tls: Use __sk_dst_get() and dst_dev_rcu() in get_netdev_for

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Message-ID: <20260112063546.2969089-3-keerthana.kalyanasundaram@broadcom.com>
Date: Mon, 12 Jan 2026 06:35:46 +0000
From: Keerthana K <keerthana.kalyanasundaram@...adcom.com>
To: stable@...r.kernel.org,
	gregkh@...uxfoundation.org
Cc: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	yoshfuji@...ux-ipv6.org,
	dsahern@...nel.org,
	borisp@...dia.com,
	john.fastabend@...il.com,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org,
	ajay.kaher@...adcom.com,
	alexey.makhalov@...adcom.com,
	vamsi-krishna.brahmajosyula@...adcom.com,
	yin.ding@...adcom.com,
	tapas.kundu@...adcom.com,
	Kuniyuki Iwashima <kuniyu@...gle.com>,
	Sabrina Dubroca <sd@...asysnail.net>,
	Sasha Levin <sashal@...nel.org>,
	Keerthana K <keerthana.kalyanasundaram@...adcom.com>
Subject: [PATCH v5.15-v6.1 2/2] tls: Use __sk_dst_get() and dst_dev_rcu() in get_netdev_for_sock().

From: Kuniyuki Iwashima <kuniyu@...gle.com>

[ Upstream commit c65f27b9c3be2269918e1cbad6d8884741f835c5 ]

get_netdev_for_sock() is called during setsockopt(),
so not under RCU.

Using sk_dst_get(sk)->dev could trigger UAF.

Let's use __sk_dst_get() and dst_dev_rcu().

Note that the only ->ndo_sk_get_lower_dev() user is
bond_sk_get_lower_dev(), which uses RCU.

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Reviewed-by: Sabrina Dubroca <sd@...asysnail.net>
Link: https://patch.msgid.link/20250916214758.650211-6-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
[ Keerthana: Backport to v5.15-v6.1 ]
Signed-off-by: Keerthana K <keerthana.kalyanasundaram@...adcom.com>
---
 net/tls/tls_device.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index c51377a15..e79bce6db 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -125,17 +125,19 @@ static void tls_device_queue_ctx_destruction(struct tls_context *ctx)
 /* We assume that the socket is already connected */
 static struct net_device *get_netdev_for_sock(struct sock *sk)
 {
-	struct dst_entry *dst = sk_dst_get(sk);
-	struct net_device *netdev = NULL;
+	struct net_device *dev, *lowest_dev = NULL;
+	struct dst_entry *dst;
 
-	if (likely(dst)) {
-		netdev = netdev_sk_get_lowest_dev(dst->dev, sk);
-		dev_hold(netdev);
+	rcu_read_lock();
+	dst = __sk_dst_get(sk);
+	dev = dst ? dst_dev_rcu(dst) : NULL;
+	if (likely(dev)) {
+		lowest_dev = netdev_sk_get_lowest_dev(dev, sk);
+		dev_hold(lowest_dev);
 	}
+	rcu_read_unlock();
 
-	dst_release(dst);
-
-	return netdev;
+	return lowest_dev;
 }
 
 static void destroy_record(struct tls_record_info *record)
-- 
2.43.7