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 E2FFFC433F5 for ; Mon, 14 Feb 2022 09:49:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245567AbiBNJth (ORCPT ); Mon, 14 Feb 2022 04:49:37 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:42974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344151AbiBNJqn (ORCPT ); Mon, 14 Feb 2022 04:46:43 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E897766628; Mon, 14 Feb 2022 01:40:15 -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 6CB956117D; Mon, 14 Feb 2022 09:40:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E114C340E9; Mon, 14 Feb 2022 09:40:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644831609; bh=bGyyTllWn9VeEU87vfFmIRuIH3toa/eBi1YJ/SiYrRQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RhoUhwAvqKPxMV5WK4VdatxA4tCJ+GMQ93uE36grwze9MRVWIvIf/pyDl3zWzi05S JMfEqZw4QEPPzCZjp91OXRVcs5uzSL656BuEGyWlNYyBS2UMJfouMCAj5mXFtie20b juWH8Xx0iYImH6VI0ByQMEms/2zftt/BckaELEdw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+4c63f36709a642f801c5@syzkaller.appspotmail.com, Ziyang Xuan , Oliver Hartkopp , Marc Kleine-Budde Subject: [PATCH 5.10 006/116] can: isotp: fix potential CAN frame reception race in isotp_rcv() Date: Mon, 14 Feb 2022 10:25:05 +0100 Message-Id: <20220214092458.895195012@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220214092458.668376521@linuxfoundation.org> References: <20220214092458.668376521@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: linux-kernel@vger.kernel.org From: Oliver Hartkopp commit 7c759040c1dd03954f650f147ae7175476d51314 upstream. When receiving a CAN frame the current code logic does not consider concurrently receiving processes which do not show up in real world usage. Ziyang Xuan writes: The following syz problem is one of the scenarios. so->rx.len is changed by isotp_rcv_ff() during isotp_rcv_cf(), so->rx.len equals 0 before alloc_skb() and equals 4096 after alloc_skb(). That will trigger skb_over_panic() in skb_put(). ======================================================= CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc8-syzkaller #0 RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:113 Call Trace: skb_over_panic net/core/skbuff.c:118 [inline] skb_put.cold+0x24/0x24 net/core/skbuff.c:1990 isotp_rcv_cf net/can/isotp.c:570 [inline] isotp_rcv+0xa38/0x1e30 net/can/isotp.c:668 deliver net/can/af_can.c:574 [inline] can_rcv_filter+0x445/0x8d0 net/can/af_can.c:635 can_receive+0x31d/0x580 net/can/af_can.c:665 can_rcv+0x120/0x1c0 net/can/af_can.c:696 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5465 __netif_receive_skb+0x24/0x1b0 net/core/dev.c:5579 Therefore we make sure the state changes and data structures stay consistent at CAN frame reception time by adding a spin_lock in isotp_rcv(). This fixes the issue reported by syzkaller but does not affect real world operation. Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol") Link: https://lore.kernel.org/linux-can/d7e69278-d741-c706-65e1-e87623d9a8e8@huawei.com/T/ Link: https://lore.kernel.org/all/20220208200026.13783-1-socketcan@hartkopp.net Cc: stable@vger.kernel.org Reported-by: syzbot+4c63f36709a642f801c5@syzkaller.appspotmail.com Reported-by: Ziyang Xuan Signed-off-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- net/can/isotp.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) --- a/net/can/isotp.c +++ b/net/can/isotp.c @@ -56,6 +56,7 @@ #include #include #include +#include #include #include #include @@ -145,6 +146,7 @@ struct isotp_sock { struct tpcon rx, tx; struct list_head notifier; wait_queue_head_t wait; + spinlock_t rx_lock; /* protect single thread state machine */ }; static LIST_HEAD(isotp_notifier_list); @@ -615,11 +617,17 @@ static void isotp_rcv(struct sk_buff *sk n_pci_type = cf->data[ae] & 0xF0; + /* Make sure the state changes and data structures stay consistent at + * CAN frame reception time. This locking is not needed in real world + * use cases but the inconsistency can be triggered with syzkaller. + */ + spin_lock(&so->rx_lock); + if (so->opt.flags & CAN_ISOTP_HALF_DUPLEX) { /* check rx/tx path half duplex expectations */ if ((so->tx.state != ISOTP_IDLE && n_pci_type != N_PCI_FC) || (so->rx.state != ISOTP_IDLE && n_pci_type == N_PCI_FC)) - return; + goto out_unlock; } switch (n_pci_type) { @@ -668,6 +676,9 @@ static void isotp_rcv(struct sk_buff *sk isotp_rcv_cf(sk, cf, ae, skb); break; } + +out_unlock: + spin_unlock(&so->rx_lock); } static void isotp_fill_dataframe(struct canfd_frame *cf, struct isotp_sock *so, @@ -1407,6 +1418,7 @@ static int isotp_init(struct sock *sk) so->txtimer.function = isotp_tx_timer_handler; init_waitqueue_head(&so->wait); + spin_lock_init(&so->rx_lock); spin_lock(&isotp_notifier_lock); list_add_tail(&so->notifier, &isotp_notifier_list);