From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B8EB536826E; Wed, 30 Sep 2026 19:29:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790796596; cv=none; b=opxC8Kg4XLbb1RQ6JeHyAf8LUYqBsKFg3xaHdt88qvRHZMcJzdXfCv8XyiXI13JH6fwYEkkUX19wxQmEoEvFdGvMyP0oOgiR1GjOfUZfWhZCp5tENhwKbNjRh0i5diQrg0fh8U66OXG7WwDo761HGWMlDL0hO0Kp+ktjmi2CwGg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790796596; c=relaxed/simple; bh=IBZca43xVhR91w+BcyeECVkyQN94YQ9lPn+Jstq7Bwk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Y+kqyjpV2WesSJgJurgAYZyZXbZb4x/NWlZQfJqmuTH6i+3lTaOAe+uxXNMyTNyv/uWFKeFTHrqwMq6wbvXVPoA6o5SMUQZNx+JvhxO2Rbv7/0E4a73frNxM/3rGqgjvjMx6budgacrZZXFItoL0GDJRSc7DnpIwsF4k9zGADqQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bTRyLR2M; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="bTRyLR2M" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 252B41F000FF; Wed, 30 Sep 2026 19:29:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790796595; bh=zaRUrhWu4yA2/o9sfJs9NpoRbNUa6GV6zpEqERlrBQA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bTRyLR2MO3voEImPWQZlzz4Ji3BgiE3qEsX9JUPfTnBfkNtAdFMyBwlb8pi0plOEz om2Uqs8azf/AyozsM6qUqwrtflokhAkKm9INhsEHi+nMErEVwygn+VVSRPNBLACC9z 2OydGrUqD44OY3bzTBtmgRsOGAsyobPpAc8G/90w= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jakub Sitnicki , Jiayuan Chen , Geliang Tang , Emil Tsalapatis , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.6 0969/1193] bpf, sockmap: Fix self-redirect copied_seq double-counting Date: Wed, 30 Sep 2026 17:27:33 +0200 Message-ID: <20260930152455.774313756@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Geliang Tang [ Upstream commit 490a83d6386eec1d29f470c8d7331677fb46c3b7 ] When a BPF stream_verdict program redirects an skb back to the same socket (self-redirect with BPF_F_INGRESS), sk_psock_verdict_apply() calls tcp_eat_skb() which advances tcp_sk->copied_seq. However, the skb is then delivered to the socket's psock ingress queue and later read by tcp_bpf_recvmsg_parser(), which also advances copied_seq via the copied_from_self accounting path. This double-counting causes copied_seq to advance by 2x the actual data length, triggering: TCP recvmsg seq # bug 2: copied BF2E806, seq BF2E7FD, \ rcvnxt BF2E806, fl 0 WARNING: net/ipv4/tcp.c:2745 at tcp_recvmsg_locked+0x72b/0x2640 Call Trace: tcp_recvmsg+0x10a/0x500 sock_recvmsg+0x168/0x1d0 __sys_recvfrom+0x19a/0x2a0 __x64_sys_recvfrom+0xe4/0x1f0 do_syscall_64+0xf7/0x530 entry_SYSCALL_64_after_hwframe+0x77/0x7f cleanup rbuf bug: copied BF2E806 seq BF2E806 rcvnxt BF2E806 WARNING: net/ipv4/tcp.c:1609 at tcp_cleanup_rbuf+0xf2/0x1c0 Call Trace: tcp_recvmsg_locked+0x8d1/0x2640 tcp_recvmsg+0x10a/0x500 sock_recvmsg+0x168/0x1d0 __sys_recvfrom+0x19a/0x2a0 __x64_sys_recvfrom+0xe4/0x1f0 do_syscall_64+0xf7/0x530 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fix this by converting self-redirect verdict to __SK_PASS at the beginning of sk_psock_verdict_apply(). This bypasses the __SK_REDIRECT case entirely (which calls sk_psock_eat_skb), letting the __SK_PASS path queue the skb to the psock ingress queue. The data is then read via tcp_bpf_recvmsg_parser(), which advances copied_seq exactly once through copied_from_self. Cross-socket redirects continue through __SK_REDIRECT with sk_psock_eat_skb() unchanged. Fixes: e5c6de5fa025 ("bpf, sockmap: Incorrectly handling copied_seq") Suggested-by: Jakub Sitnicki Suggested-by: Jiayuan Chen Signed-off-by: Geliang Tang Reviewed-by: Emil Tsalapatis Reviewed-by: Jiayuan Chen Link: https://lore.kernel.org/r/1a8e797a1b26e2f695aaac22ac644c2862f63466.1788858299.git.tanggeliang@kylinos.cn Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- net/core/skmsg.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 565229dfd3f28..819a289e4bdd5 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -1035,6 +1035,10 @@ static int sk_psock_verdict_apply(struct sk_psock *psock, struct sk_buff *skb, int err = 0; u32 len, off; + if (verdict == __SK_REDIRECT && skb_bpf_ingress(skb) && + skb_bpf_redirect_fetch(skb) == psock->sk) + verdict = __SK_PASS; + switch (verdict) { case __SK_PASS: err = -EIO; -- 2.53.0