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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: 6648e61 ("bpf, skmsg: Fix NULL pointer dereference in sk_psock_skb_ingress_enqueue") Reported-by: Vincent Whitchurch <vincent.whitchurch@datadoghq.com> Signed-off-by: Jiayuan Chen <mrpre@163.com> Signed-off-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Link: https://patch.msgid.link/20241118030910.36230-2-mrpre@163.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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net/core/skmsg.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1117,9 +1117,9 @@ static void sk_psock_strp_data_ready(struct sock *sk)
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if (tls_sw_has_ctx_rx(sk)) {
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psock->saved_data_ready(sk);
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} else {
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write_lock_bh(&sk->sk_callback_lock);
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read_lock_bh(&sk->sk_callback_lock);
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strp_data_ready(&psock->strp);
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write_unlock_bh(&sk->sk_callback_lock);
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read_unlock_bh(&sk->sk_callback_lock);
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}
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}
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rcu_read_unlock();

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