From: Luxiao Xu Date: Tue, 4 Aug 2026 14:29:01 +0000 (+0800) Subject: bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=31a420a822ff92e2090bd5d65efe8e34e2d6d9b8;p=thirdparty%2Fkernel%2Flinux.git bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie accept a socket pointer 'sk' with argument type ARG_PTR_TO_BTF_ID_SOCK_COMMON. However, they access sk->sk_protocol without validating whether 'sk' represents a full socket. Fix this issue by checking sk->sk_state != TCP_LISTEN before inspecting sk->sk_protocol in both bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie. Since mini-sockets are never in the TCP_LISTEN state, the condition short-circuits and prevents dereferencing fullsock-specific fields. Fixes: 399040847084 ("bpf: add helper to check for a valid SYN cookie") Fixes: 70d66244317e ("bpf: add bpf_tcp_gen_syncookie helper") Reported-by: Vega Signed-off-by: Luxiao Xu Signed-off-by: Ren Wei Signed-off-by: Daniel Borkmann Reviewed-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://lore.kernel.org/bpf/6218aa3534d0d2d3f448fde70a8dc2769d7a8201.1785823138.git.rakukuip@gmail.com --- diff --git a/net/core/filter.c b/net/core/filter.c index 11bb0d236822..16845987b244 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7684,7 +7684,7 @@ BPF_CALL_5(bpf_tcp_check_syncookie, struct sock *, sk, void *, iph, u32, iph_len return -EINVAL; /* sk_listener() allows TCP_NEW_SYN_RECV, which makes no sense here. */ - if (sk->sk_protocol != IPPROTO_TCP || sk->sk_state != TCP_LISTEN) + if (sk->sk_state != TCP_LISTEN || sk->sk_protocol != IPPROTO_TCP) return -EINVAL; if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_syncookies)) @@ -7757,7 +7757,7 @@ BPF_CALL_5(bpf_tcp_gen_syncookie, struct sock *, sk, void *, iph, u32, iph_len, if (unlikely(!sk || th_len < sizeof(*th) || th_len != th->doff * 4)) return -EINVAL; - if (sk->sk_protocol != IPPROTO_TCP || sk->sk_state != TCP_LISTEN) + if (sk->sk_state != TCP_LISTEN || sk->sk_protocol != IPPROTO_TCP) return -EINVAL; if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_syncookies))