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

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-12-28 · updated 2026-08-04
Weakness: CWE-667

Description

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

Affected products

Linux kernel: from 5.10.223 before 5.11; from 5.15.159 before 5.15.174; from 6.1.91 before 6.1.120; from 6.6.31 before 6.6.64; from 6.8.10 before 6.11.11; from 6.12 before 6.12.2 — fixed in 5.11, 5.15.174, 6.1.120, 6.11.11, 6.12.2, 6.6.64

How to fix

Upgrade to a fixed version: Linux kernel 5.11, 5.15.174, 6.1.120, 6.11.11. Check the vendor advisory for mitigations.

References

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