Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752196AbdLFMub (ORCPT ); Wed, 6 Dec 2017 07:50:31 -0500 Received: from mail-pl0-f68.google.com ([209.85.160.68]:34394 "EHLO mail-pl0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750989AbdLFMu0 (ORCPT ); Wed, 6 Dec 2017 07:50:26 -0500 X-Google-Smtp-Source: AGs4zMbEqI5+b/6zqjKfQGuxQCyKyxHLUNqYHXNgenVEWmUcmI6HclaXqJmrTCjBeU1XrulRi1odH97aUlYob4o6w+s= MIME-Version: 1.0 In-Reply-To: References: <089e0825d42484310b055c75c3f6@google.com> <20171026175847.GH59538@devbig577.frc2.facebook.com> From: Dmitry Vyukov Date: Wed, 6 Dec 2017 13:50:04 +0100 Message-ID: Subject: Re: KASAN: use-after-free Read in get_work_pool To: Cong Wang Cc: Tejun Heo , syzbot , Lai Jiangshan , LKML , syzkaller-bugs@googlegroups.com, David Miller , tom@quantonium.net, Eric Dumazet , Eric Biggers , netdev Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3243 Lines: 78 On Fri, Oct 27, 2017 at 11:18 PM, Cong Wang wrote: > On Thu, Oct 26, 2017 at 11:00 PM, Dmitry Vyukov wrote: >> On Thu, Oct 26, 2017 at 7:58 PM, Tejun Heo wrote: >>> Hello, >>> >>> On Thu, Oct 26, 2017 at 09:35:44AM -0700, syzbot wrote: >>>> BUG: KASAN: use-after-free in __read_once_size >>>> include/linux/compiler.h:276 [inline] >>>> BUG: KASAN: use-after-free in atomic64_read >>>> arch/x86/include/asm/atomic64_64.h:21 [inline] >>>> BUG: KASAN: use-after-free in atomic_long_read >>>> include/asm-generic/atomic-long.h:44 [inline] >>>> BUG: KASAN: use-after-free in get_work_pool+0x1c2/0x1e0 >>>> kernel/workqueue.c:709 >>>> Read of size 8 at addr ffff8801cc58c378 by task syz-executor5/21326 >>>> >>>> CPU: 1 PID: 21326 Comm: syz-executor5 Not tainted 4.13.0+ #43 >>>> Hardware name: Google Google Compute Engine/Google Compute Engine, >>>> BIOS Google 01/01/2011 >>>> Call Trace: >>>> __dump_stack lib/dump_stack.c:16 [inline] >>>> dump_stack+0x194/0x257 lib/dump_stack.c:52 >>>> print_address_description+0x73/0x250 mm/kasan/report.c:252 >>>> kasan_report_error mm/kasan/report.c:351 [inline] >>>> kasan_report+0x24e/0x340 mm/kasan/report.c:409 >>>> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 >>>> __read_once_size include/linux/compiler.h:276 [inline] >>>> atomic64_read arch/x86/include/asm/atomic64_64.h:21 [inline] >>>> atomic_long_read include/asm-generic/atomic-long.h:44 [inline] >>>> get_work_pool+0x1c2/0x1e0 kernel/workqueue.c:709 >>>> __queue_work+0x235/0x1150 kernel/workqueue.c:1401 >>>> queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1486 >>>> queue_work include/linux/workqueue.h:489 [inline] >>>> strp_check_rcv+0x25/0x30 net/strparser/strparser.c:553 >>>> kcm_attach net/kcm/kcmsock.c:1439 [inline] >>>> kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline] >>>> kcm_ioctl+0x826/0x1610 net/kcm/kcmsock.c:1695 >>>> sock_do_ioctl+0x65/0xb0 net/socket.c:961 >>>> sock_ioctl+0x2c2/0x440 net/socket.c:1058 >>>> vfs_ioctl fs/ioctl.c:45 [inline] >>>> do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685 >>>> SYSC_ioctl fs/ioctl.c:700 [inline] >>>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 >>>> entry_SYSCALL_64_fastpath+0x1f/0xbe >>> >>> Looks like kcm is trying to reuse a work item whose last workqueue has >>> been destroyed without re-initing it. A work item needs to be >>> reinit'd. >> >> +kcm maintainers > > Can you try the fix below? There is no C reproducer so I can't verify it. Hi Cong, syzbot can now test proposed patches, see https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot for details. Please give it a try. > diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c > index af4e76ac88ff..7816f44c576a 100644 > --- a/net/kcm/kcmsock.c > +++ b/net/kcm/kcmsock.c > @@ -1433,11 +1433,12 @@ static int kcm_attach(struct socket *sock, > struct socket *csock, > KCM_STATS_INCR(mux->stats.psock_attach); > mux->psocks_cnt++; > psock_now_avail(psock); > - spin_unlock_bh(&mux->lock); > > /* Schedule RX work in case there are already bytes queued */ > strp_check_rcv(&psock->strp); > > + spin_unlock_bh(&mux->lock); > + > return 0; > }