From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F0E06C433EF for ; Mon, 7 Mar 2022 10:12:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239820AbiCGKNJ (ORCPT ); Mon, 7 Mar 2022 05:13:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242946AbiCGKMC (ORCPT ); Mon, 7 Mar 2022 05:12:02 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C12D18CD86; Mon, 7 Mar 2022 01:56:17 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E218C60BB9; Mon, 7 Mar 2022 09:56:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF564C340E9; Mon, 7 Mar 2022 09:56:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646646974; bh=hYrHolxhejP1P56cX192JntSs5k6cVUspjS5k2gajVI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tMg5EZklbW5NES4Fp3xA230Zl3p0fjPKoVsHnaTbrsXgNsWNvZb+/HycXNnne/HXX 9R2VHxgjV254eSo0Vd84t76wY6D3Mq4ZwKtlzXnCDL8ZQKeB1Q1cjgJKIJTVzNEFQ/ rGzlxvf5EAwEqQrG7rw4zTqVzmvOSyEdjSJRhJZE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Paolo Abeni , Mat Martineau , Jakub Kicinski Subject: [PATCH 5.16 111/186] mptcp: Correctly set DATA_FIN timeout when number of retransmits is large Date: Mon, 7 Mar 2022 10:19:09 +0100 Message-Id: <20220307091657.182305927@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220307091654.092878898@linuxfoundation.org> References: <20220307091654.092878898@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mat Martineau commit 877d11f0332cd2160e19e3313e262754c321fa36 upstream. Syzkaller with UBSAN uncovered a scenario where a large number of DATA_FIN retransmits caused a shift-out-of-bounds in the DATA_FIN timeout calculation: ================================================================================ UBSAN: shift-out-of-bounds in net/mptcp/protocol.c:470:29 shift exponent 32 is too large for 32-bit type 'unsigned int' CPU: 1 PID: 13059 Comm: kworker/1:0 Not tainted 5.17.0-rc2-00630-g5fbf21c90c60 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Workqueue: events mptcp_worker Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 ubsan_epilogue+0xb/0x5a lib/ubsan.c:151 __ubsan_handle_shift_out_of_bounds.cold+0xb2/0x20e lib/ubsan.c:330 mptcp_set_datafin_timeout net/mptcp/protocol.c:470 [inline] __mptcp_retrans.cold+0x72/0x77 net/mptcp/protocol.c:2445 mptcp_worker+0x58a/0xa70 net/mptcp/protocol.c:2528 process_one_work+0x9df/0x16d0 kernel/workqueue.c:2307 worker_thread+0x95/0xe10 kernel/workqueue.c:2454 kthread+0x2f4/0x3b0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 ================================================================================ This change limits the maximum timeout by limiting the size of the shift, which keeps all intermediate values in-bounds. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/259 Fixes: 6477dd39e62c ("mptcp: Retransmit DATA_FIN") Acked-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/mptcp/protocol.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -464,9 +464,12 @@ static bool mptcp_pending_data_fin(struc static void mptcp_set_datafin_timeout(const struct sock *sk) { struct inet_connection_sock *icsk = inet_csk(sk); + u32 retransmits; - mptcp_sk(sk)->timer_ival = min(TCP_RTO_MAX, - TCP_RTO_MIN << icsk->icsk_retransmits); + retransmits = min_t(u32, icsk->icsk_retransmits, + ilog2(TCP_RTO_MAX / TCP_RTO_MIN)); + + mptcp_sk(sk)->timer_ival = TCP_RTO_MIN << retransmits; } static void __mptcp_set_timeout(struct sock *sk, long tout)