bpf, skmsg: fix verdict sk_data_ready racing with ktls rx

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sk_psock_strp_data_ready() already checks tls_sw_has_ctx_rx() and
defers to psock->saved_data_ready when a TLS RX context is present,
avoiding a conflict with the TLS strparser's ownership of the receive
queue (commit e91de6afa8, "bpf: Fix running sk_skb program types
with ktls").

sk_psock_verdict_data_ready() has no equivalent guard.  When a socket
is inserted into a sockmap (BPF_SK_SKB_VERDICT) before TLS RX is
configured, tls_sw_strparser_arm() saves sk_psock_verdict_data_ready
as rx_ctx->saved_data_ready.  On data arrival:

  tls_data_ready -> tls_strp_data_ready -> tls_rx_msg_ready
    -> saved_data_ready() = sk_psock_verdict_data_ready()
      -> tcp_read_skb() drains sk_receive_queue via __skb_unlink()
         without calling tcp_eat_skb(), so copied_seq is not advanced.

tls_strp_msg_load() then finds tcp_inq() >= full_len (stale), calls
tcp_recv_skb() on the now-empty queue, hits WARN_ON_ONCE(!first), and
returns with rx_ctx->strp.anchor.frag_list pointing at a psock-owned
(potentially freed) skb.  tls_decrypt_sg() subsequently walks that
frag_list: use-after-free.

Apply the same fix as sk_psock_strp_data_ready(): if a TLS RX context
is present, call psock->saved_data_ready (sock_def_readable) to wake
recv() waiters and return immediately, leaving the receive queue
untouched.  TLS retains sole ownership of the queue and decrypts the
record normally through tls_sw_recvmsg().

Fixes: ef5659280e ("bpf, sockmap: Allow skipping sk_skb parser program")
Signed-off-by: Xingwang Xiang <v3rdant.xiang@gmail.com>
Link: https://patch.msgid.link/20260517145630.20521-2-v3rdant.xiang@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

...

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Xingwang Xiang 2026-05-17 23:56:26 +09:00 • committed by Jakub Kicinski

parent e7c70bf97e

commit ddf8029623

1 changed files with 7 additions and 2 deletions

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net/core/skmsg.c

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