6.1-stable review patch. If anyone has any objections, please let me know.
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From: Jiayuan Chen mrpre@163.com
[ Upstream commit 8ca2a1eeadf09862190b2810697702d803ceef2d ]
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@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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 746d950de0e14..584516387fdab 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -1114,9 +1114,9 @@ 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();