CVE-2024-56694 — bpf: fix recursive lock when verdict program return SK_PASS

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

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

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CVE-2024-56694 — bpf: fix recursive lock when verdict program return SK_PASS