From patchwork Mon Oct 7 14:15:57 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuniyuki Iwashima X-Patchwork-Id: 13824772 X-Patchwork-Delegate: kuba@kernel.org Received: from smtp-fw-33001.amazon.com (smtp-fw-33001.amazon.com [207.171.190.10]) (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 97D4A1D4615 for ; Mon, 7 Oct 2024 14:16:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=207.171.190.10 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728310596; cv=none; b=RxYQyzyFHSxhdrsJAB7EloNkKupj9FeiV4UlkA/cemAm9vpV54lNUxtXQ3ceYbSQMVPJgMFv0sWpkUfq7sMqn13fK8AwzBMEIwMXRzAeXTP4C/8kRwRAyhLL3RZ8+amuyE50kukZzaihfPwa1CT8dJiZQbMPXRaxjvirMjkA9p4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728310596; c=relaxed/simple; bh=6gescgr2qfMQaiP8GKnPvJeVVumxrTGcysvIxcyKBEk=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=ZcKdGBxW+27LJcMp2POzYyrKcSpTnYAwaItWSbSaDGRsakChr34rrsym/pCofXCJhv7vn7vuBnR+NTxWJV1IQkUSfd1ybX8kfcpas9W62nmoY265dK0L0COYMMPTs8CrdFZD2QIbCMcxUgENOsfHR+34Dh3Mvn1HB90tYZSLJ+w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.jp; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=XGHxnsDp; arc=none smtp.client-ip=207.171.190.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.jp Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="XGHxnsDp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1728310595; x=1759846595; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=uaXf9a0Ae6PtW41MClDH0kSO7SZYrf3cLUh2I9CJwgk=; b=XGHxnsDp0CoF7JJD+qdazVGWbEDhDEt4OnAS0L+ucFxeU9bgMQdUl146 iTKMYkfUVQQxRzcNc8gQT8nZPGtK1TnJZCeRzkLNIiBT3F1bmVV1ZZJb9 SBMK71SILljEQPbmnsEjXZZ65YC8U7rowUn1pbSKpmwC0r6HEsebjcOOI 0=; X-IronPort-AV: E=Sophos;i="6.11,184,1725321600"; d="scan'208";a="373877489" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.25.36.210]) by smtp-border-fw-33001.sea14.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Oct 2024 14:16:22 +0000 Received: from EX19MTAUWC002.ant.amazon.com [10.0.7.35:12008] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.41.198:2525] with esmtp (Farcaster) id 97cbb39e-a454-4b7f-9452-25f6bbe03066; Mon, 7 Oct 2024 14:16:22 +0000 (UTC) X-Farcaster-Flow-ID: 97cbb39e-a454-4b7f-9452-25f6bbe03066 Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWC002.ant.amazon.com (10.250.64.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Mon, 7 Oct 2024 14:16:21 +0000 Received: from 88665a182662.ant.amazon.com (10.119.221.239) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.35; Mon, 7 Oct 2024 14:16:19 +0000 From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , David Ahern CC: Martin KaFai Lau , Kuniyuki Iwashima , Kuniyuki Iwashima , Subject: [PATCH v1 net] tcp/dccp: Don't use timer_pending() in reqsk_queue_unlink(). Date: Mon, 7 Oct 2024 07:15:57 -0700 Message-ID: <20241007141557.14424-1-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D031UWA001.ant.amazon.com (10.13.139.88) To EX19D004ANA001.ant.amazon.com (10.37.240.138) X-Patchwork-Delegate: kuba@kernel.org Martin KaFai Lau reported use-after-free [0] in reqsk_timer_handler(). """ We are seeing a use-after-free from a bpf prog attached to trace_tcp_retransmit_synack. The program passes the req->sk to the bpf_sk_storage_get_tracing kernel helper which does check for null before using it. """ The commit 83fccfc3940c ("inet: fix potential deadlock in reqsk_queue_unlink()") added timer_pending() in reqsk_queue_unlink() not to call del_timer_sync() from reqsk_timer_handler(), but it introduced a small race window. Before the timer is called, expire_timers() calls detach_timer(timer, true) to clear timer->entry.pprev and marks it as not pending. If reqsk_queue_unlink() checks timer_pending() just before expire_timers() calls detach_timer(), TCP will miss del_timer_sync(); the reqsk timer will continue running and send multiple SYN+ACKs until it expires. The reported UAF could happen if req->sk is close()d earlier than the timer expiration. Let's not use timer_pending() by passing the caller context to __inet_csk_reqsk_queue_drop(). [0] BUG: KFENCE: use-after-free read in bpf_sk_storage_get_tracing+0x2e/0x1b0 Use-after-free read at 0x00000000a891fb3a (in kfence-#1): bpf_sk_storage_get_tracing+0x2e/0x1b0 bpf_prog_5ea3e95db6da0438_tcp_retransmit_synack+0x1d20/0x1dda bpf_trace_run2+0x4c/0xc0 tcp_rtx_synack+0xf9/0x100 reqsk_timer_handler+0xda/0x3d0 run_timer_softirq+0x292/0x8a0 irq_exit_rcu+0xf5/0x320 sysvec_apic_timer_interrupt+0x6d/0x80 asm_sysvec_apic_timer_interrupt+0x16/0x20 intel_idle_irq+0x5a/0xa0 cpuidle_enter_state+0x94/0x273 cpu_startup_entry+0x15e/0x260 start_secondary+0x8a/0x90 secondary_startup_64_no_verify+0xfa/0xfb kfence-#1: 0x00000000a72cc7b6-0x00000000d97616d9, size=2376, cache=TCPv6 allocated by task 0 on cpu 9 at 260507.901592s: sk_prot_alloc+0x35/0x140 sk_clone_lock+0x1f/0x3f0 inet_csk_clone_lock+0x15/0x160 tcp_create_openreq_child+0x1f/0x410 tcp_v6_syn_recv_sock+0x1da/0x700 tcp_check_req+0x1fb/0x510 tcp_v6_rcv+0x98b/0x1420 ipv6_list_rcv+0x2258/0x26e0 napi_complete_done+0x5b1/0x2990 mlx5e_napi_poll+0x2ae/0x8d0 net_rx_action+0x13e/0x590 irq_exit_rcu+0xf5/0x320 common_interrupt+0x80/0x90 asm_common_interrupt+0x22/0x40 cpuidle_enter_state+0xfb/0x273 cpu_startup_entry+0x15e/0x260 start_secondary+0x8a/0x90 secondary_startup_64_no_verify+0xfa/0xfb freed by task 0 on cpu 9 at 260507.927527s: rcu_core_si+0x4ff/0xf10 irq_exit_rcu+0xf5/0x320 sysvec_apic_timer_interrupt+0x6d/0x80 asm_sysvec_apic_timer_interrupt+0x16/0x20 cpuidle_enter_state+0xfb/0x273 cpu_startup_entry+0x15e/0x260 start_secondary+0x8a/0x90 secondary_startup_64_no_verify+0xfa/0xfb Fixes: 83fccfc3940c ("inet: fix potential deadlock in reqsk_queue_unlink()") Reported-by: Martin KaFai Lau Closes: https://lore.kernel.org/netdev/eb6684d0-ffd9-4bdc-9196-33f690c25824@linux.dev/ Signed-off-by: Kuniyuki Iwashima --- net/ipv4/inet_connection_sock.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 2c5632d4fddb..36f03d51356e 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -1045,12 +1045,13 @@ static bool reqsk_queue_unlink(struct request_sock *req) found = __sk_nulls_del_node_init_rcu(sk); spin_unlock(lock); } - if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer)) - reqsk_put(req); + return found; } -bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req) +static bool __inet_csk_reqsk_queue_drop(struct sock *sk, + struct request_sock *req, + bool from_timer) { bool unlinked = reqsk_queue_unlink(req); @@ -1058,8 +1059,17 @@ bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req) reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req); reqsk_put(req); } + + if (!from_timer && timer_delete_sync(&req->rsk_timer)) + reqsk_put(req); + return unlinked; } + +bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req) +{ + return __inet_csk_reqsk_queue_drop(sk, req, false); +} EXPORT_SYMBOL(inet_csk_reqsk_queue_drop); void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req) @@ -1152,7 +1162,7 @@ static void reqsk_timer_handler(struct timer_list *t) if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) { /* delete timer */ - inet_csk_reqsk_queue_drop(sk_listener, nreq); + __inet_csk_reqsk_queue_drop(sk_listener, nreq, true); goto no_ownership; } @@ -1178,7 +1188,8 @@ static void reqsk_timer_handler(struct timer_list *t) } drop: - inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq); + __inet_csk_reqsk_queue_drop(sk_listener, nreq, true); + reqsk_put(req); } static bool reqsk_queue_hash_req(struct request_sock *req,