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 B6017C6379F for ; Fri, 13 Jan 2023 23:41:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230356AbjAMXld (ORCPT ); Fri, 13 Jan 2023 18:41:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230445AbjAMXlc (ORCPT ); Fri, 13 Jan 2023 18:41:32 -0500 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A69428CBFB for ; Fri, 13 Jan 2023 15:41:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1673653291; x=1705189291; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=inIfniUrhA7Kcp3SOztVdGaFs+LAOGmS5e0FBy+I3Tc=; b=ZujS7jkXGHzWUCThpq0PPLfkhX1C/BRvqYZZrKhKsb4BIaYWqOTJA9FQ 4KaOs0WeTJkdbrNWSMHlsVjeW7PoOSBTAn5fQNBXzVSHF2BxJca9lqqpK kld28oGTlF6JRwL9U2SANeajYKe4ZGaCUT0fEghBUbEHcSZQDmT0FmbeM aEYOfwogVRo4xRijWqxjP5kPWzaLWJGiTbtAsowsPhUqVWleZaZ7osJ/f 60PHneJXPCoFRzlBOPMSTOTfaCLotv7n30u4q1+LaiQHhHzAhP+S9eLpn 4zDdxogWiORaddpkcaIRlgtpWXoM9iCm8RU4QTvL7QpdKwV8jJrecIgyb g==; X-IronPort-AV: E=McAfee;i="6500,9779,10589"; a="326186662" X-IronPort-AV: E=Sophos;i="5.97,215,1669104000"; d="scan'208";a="326186662" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jan 2023 15:41:31 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10589"; a="690659280" X-IronPort-AV: E=Sophos;i="5.97,215,1669104000"; d="scan'208";a="690659280" Received: from namnguy3-mobl.amr.corp.intel.com (HELO vcostago-mobl3) ([10.252.142.187]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jan 2023 15:41:30 -0800 From: Vinicius Costa Gomes To: Eric Dumazet , "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet , syzbot , Alexander Potapenko Subject: Re: [PATCH net] net/sched: sch_taprio: fix possible use-after-free In-Reply-To: <20230113164849.4004848-1-edumazet@google.com> References: <20230113164849.4004848-1-edumazet@google.com> Date: Fri, 13 Jan 2023 15:41:30 -0800 Message-ID: <871qny9f4l.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi, Eric Dumazet writes: > syzbot reported a nasty crash [1] in net_tx_action() which > made little sense until we got a repro. > > This repro installs a taprio qdisc, but providing an > invalid TCA_RATE attribute. > > qdisc_create() has to destroy the just initialized > taprio qdisc, and taprio_destroy() is called. > > However, the hrtimer used by taprio had already fired, > therefore advance_sched() called __netif_schedule(). > > Then net_tx_action was trying to use a destroyed qdisc. > > We can not undo the __netif_schedule(), so we must wait > until one cpu serviced the qdisc before we can proceed. > > Many thanks to Alexander Potapenko for his help. > > [1] > BUG: KMSAN: uninit-value in queued_spin_trylock include/asm-generic/qspinlock.h:94 [inline] > BUG: KMSAN: uninit-value in do_raw_spin_trylock include/linux/spinlock.h:191 [inline] > BUG: KMSAN: uninit-value in __raw_spin_trylock include/linux/spinlock_api_smp.h:89 [inline] > BUG: KMSAN: uninit-value in _raw_spin_trylock+0x92/0xa0 kernel/locking/spinlock.c:138 > queued_spin_trylock include/asm-generic/qspinlock.h:94 [inline] > do_raw_spin_trylock include/linux/spinlock.h:191 [inline] > __raw_spin_trylock include/linux/spinlock_api_smp.h:89 [inline] > _raw_spin_trylock+0x92/0xa0 kernel/locking/spinlock.c:138 > spin_trylock include/linux/spinlock.h:359 [inline] > qdisc_run_begin include/net/sch_generic.h:187 [inline] > qdisc_run+0xee/0x540 include/net/pkt_sched.h:125 > net_tx_action+0x77c/0x9a0 net/core/dev.c:5086 > __do_softirq+0x1cc/0x7fb kernel/softirq.c:571 > run_ksoftirqd+0x2c/0x50 kernel/softirq.c:934 > smpboot_thread_fn+0x554/0x9f0 kernel/smpboot.c:164 > kthread+0x31b/0x430 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 > > Uninit was created at: > slab_post_alloc_hook mm/slab.h:732 [inline] > slab_alloc_node mm/slub.c:3258 [inline] > __kmalloc_node_track_caller+0x814/0x1250 mm/slub.c:4970 > kmalloc_reserve net/core/skbuff.c:358 [inline] > __alloc_skb+0x346/0xcf0 net/core/skbuff.c:430 > alloc_skb include/linux/skbuff.h:1257 [inline] > nlmsg_new include/net/netlink.h:953 [inline] > netlink_ack+0x5f3/0x12b0 net/netlink/af_netlink.c:2436 > netlink_rcv_skb+0x55d/0x6c0 net/netlink/af_netlink.c:2507 > rtnetlink_rcv+0x30/0x40 net/core/rtnetlink.c:6108 > netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] > netlink_unicast+0xf3b/0x1270 net/netlink/af_netlink.c:1345 > netlink_sendmsg+0x1288/0x1440 net/netlink/af_netlink.c:1921 > sock_sendmsg_nosec net/socket.c:714 [inline] > sock_sendmsg net/socket.c:734 [inline] > ____sys_sendmsg+0xabc/0xe90 net/socket.c:2482 > ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2536 > __sys_sendmsg net/socket.c:2565 [inline] > __do_sys_sendmsg net/socket.c:2574 [inline] > __se_sys_sendmsg net/socket.c:2572 [inline] > __x64_sys_sendmsg+0x367/0x540 net/socket.c:2572 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > CPU: 0 PID: 13 Comm: ksoftirqd/0 Not tainted 6.0.0-rc2-syzkaller-47461-gac3859c02d7f #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 > > Fixes: 5a781ccbd19e ("tc: Add support for configuring the taprio scheduler") > Reported-by: syzbot > Signed-off-by: Eric Dumazet > Cc: Alexander Potapenko > Cc: Vinicius Costa Gomes > --- > include/net/sch_generic.h | 7 +++++++ > net/sched/sch_taprio.c | 3 +++ > 2 files changed, 10 insertions(+) > > diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h > index d5517719af4ef22282f0a15b132f8e8a07ae4179..af4aa66aaa4eba8f2eacdd00bc8fef31165c6a90 100644 > --- a/include/net/sch_generic.h > +++ b/include/net/sch_generic.h > @@ -1288,4 +1288,11 @@ void mq_change_real_num_tx(struct Qdisc *sch, unsigned int new_real_tx); > > int sch_frag_xmit_hook(struct sk_buff *skb, int (*xmit)(struct sk_buff *skb)); > > +/* Make sure qdisc is no longer in SCHED state. */ > +static inline void qdisc_synchronize(const struct Qdisc *q) > +{ > + while (test_bit(__QDISC_STATE_SCHED, &q->state)) > + msleep(1); > +} > + > #endif > diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c > index 570389f6cdd7dbab5749dc06d886555305cbf623..9a11a499ea2df8d18c9c062496fdcbcf5a861391 100644 > --- a/net/sched/sch_taprio.c > +++ b/net/sched/sch_taprio.c > @@ -1700,6 +1700,8 @@ static void taprio_reset(struct Qdisc *sch) > int i; > > hrtimer_cancel(&q->advance_timer); > + qdisc_synchronize(sch); > + >From the commit message, I got the impression that only the one qdisc_synchronize() in taprio_destroy() would be needed. > if (q->qdiscs) { > for (i = 0; i < dev->num_tx_queues; i++) > if (q->qdiscs[i]) > @@ -1720,6 +1722,7 @@ static void taprio_destroy(struct Qdisc *sch) > * happens in qdisc_create(), after taprio_init() has been called. > */ > hrtimer_cancel(&q->advance_timer); > + qdisc_synchronize(sch); > > taprio_disable_offload(dev, q, NULL); > > -- > 2.39.0.314.g84b9a713c41-goog > Cheers, -- Vinicius