netdev - [PATCH net] tcp: fix possible sk_priority leak in tcp_v4_send

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Date: Thu, 11 May 2023 11:47:49 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, Antoine Tenart <atenart@...nel.org>
Subject: [PATCH net] tcp: fix possible sk_priority leak in tcp_v4_send_reset()

When tcp_v4_send_reset() is called with @sk == NULL,
we do not change ctl_sk->sk_priority, which could have been
set from a prior invocation.

Change tcp_v4_send_reset() to set sk_priority and sk_mark
fields before calling ip_send_unicast_reply().

This means tcp_v4_send_reset() and tcp_v4_send_ack()
no longer have to clear ctl_sk->sk_mark after
their call to ip_send_unicast_reply().

Fixes: f6c0f5d209fa ("tcp: honor SO_PRIORITY in TIME_WAIT state")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Antoine Tenart <atenart@...nel.org>
---
 net/ipv4/tcp_ipv4.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 39bda2b1066e1d607a59fb79c6305d0ca30cb28d..06d2573685ca993a3a0a89807f09d7b5c153cc72 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -829,6 +829,9 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
 				   inet_twsk(sk)->tw_priority : sk->sk_priority;
 		transmit_time = tcp_transmit_time(sk);
 		xfrm_sk_clone_policy(ctl_sk, sk);
+	} else {
+		ctl_sk->sk_mark = 0;
+		ctl_sk->sk_priority = 0;
 	}
 	ip_send_unicast_reply(ctl_sk,
 			      skb, &TCP_SKB_CB(skb)->header.h4.opt,
@@ -836,7 +839,6 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
 			      &arg, arg.iov[0].iov_len,
 			      transmit_time);
 
-	ctl_sk->sk_mark = 0;
 	xfrm_sk_free_policy(ctl_sk);
 	sock_net_set(ctl_sk, &init_net);
 	__TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
@@ -935,7 +937,6 @@ static void tcp_v4_send_ack(const struct sock *sk,
 			      &arg, arg.iov[0].iov_len,
 			      transmit_time);
 
-	ctl_sk->sk_mark = 0;
 	sock_net_set(ctl_sk, &init_net);
 	__TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
 	local_bh_enable();
-- 
2.40.1.521.gf1e218fcd8-goog