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Message-ID: <20241106124431.5583-1-mrpre@163.com>
Date: Wed, 6 Nov 2024 20:44:31 +0800
From: mrpre <mrpre@....com>
To: edumazet@...gle.com,
jakub@...udflare.com,
davem@...emloft.net,
dsahern@...nel.org,
kuba@...nel.org,
pabeni@...hat.com,
netdev@...r.kernel.org,
bpf@...r.kernel.orgc,
linux-kernel@...r.kernel.org
Cc: mrpre <mrpre@....com>,
Vincent Whitchurch <vincent.whitchurch@...adoghq.com>,
John Fastabend <john.fastabend@...il.com>
Subject: [PATCH bpf] bpf: fix recursive lock when verdict program return SK_PASS
When the stream_verdict program returns SK_PASS, it places the received skb
into its own receive queue, but a recursive lock eventually occurs, leading
to an operating system deadlock. This issue has been present since v6.9.
'''
sk_psock_strp_data_ready
write_lock_bh(&sk->sk_callback_lock)
strp_data_ready
strp_read_sock
read_sock -> tcp_read_sock
strp_recv
cb.rcv_msg -> sk_psock_strp_read
# now stream_verdict return SK_PASS without peer sock assign
__SK_PASS = sk_psock_map_verd(SK_PASS, NULL)
sk_psock_verdict_apply
sk_psock_skb_ingress_self
sk_psock_skb_ingress_enqueue
sk_psock_data_ready
read_lock_bh(&sk->sk_callback_lock) <= dead lock
'''
This topic has been discussed before, but it has not been fixed.
Previous discussion:
https://lore.kernel.org/all/6684a5864ec86_403d20898@john.notmuch
Fixes: 6648e613226e ("bpf, skmsg: Fix NULL pointer dereference in sk_psock_skb_ingress_enqueue")
Reported-by: Vincent Whitchurch <vincent.whitchurch@...adoghq.com>
Signed-off-by: Jiayuan Chen <mrpre@....com>
Signed-off-by: John Fastabend <john.fastabend@...il.com>
---
net/core/skmsg.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index b1dcbd3be89e..e90fbab703b2 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -1117,9 +1117,9 @@ static void sk_psock_strp_data_ready(struct sock *sk)
if (tls_sw_has_ctx_rx(sk)) {
psock->saved_data_ready(sk);
} else {
- write_lock_bh(&sk->sk_callback_lock);
+ read_lock_bh(&sk->sk_callback_lock);
strp_data_ready(&psock->strp);
- write_unlock_bh(&sk->sk_callback_lock);
+ read_unlock_bh(&sk->sk_callback_lock);
}
}
rcu_read_unlock();
--
2.43.5
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