From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753337AbdKNIKD (ORCPT ); Tue, 14 Nov 2017 03:10:03 -0500 Received: from mail-pg0-f66.google.com ([74.125.83.66]:43163 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752067AbdKNIJ5 (ORCPT ); Tue, 14 Nov 2017 03:09:57 -0500 X-Google-Smtp-Source: AGs4zMZSrdUQbzEEW1/Rnj39i4yxbB+KCv9uSRuhSXQddMTTRZZoSW9uvCkXBOm5KfM1rJltHnC4U67RFB4pjhJ7Eh8= MIME-Version: 1.0 In-Reply-To: References: <001a114a7bc08e95e7055d783ea5@google.com> From: Dmitry Vyukov Date: Tue, 14 Nov 2017 09:09:36 +0100 Message-ID: Subject: Re: KASAN: use-after-free Read in worker_thread (2) To: Cong Wang Cc: syzbot , Lai Jiangshan , LKML , syzkaller-bugs@googlegroups.com, Tejun Heo , David Miller , tom@quantonium.net, Eric Biggers , Ingo Molnar , Tobias Klauser , 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 On Fri, Nov 10, 2017 at 7:49 PM, Cong Wang wrote: > On Wed, Nov 8, 2017 at 5:00 AM, Dmitry Vyukov wrote: >> On Wed, Nov 8, 2017 at 1:58 PM, syzbot >> >> wrote: >>> Hello, >>> >>> syzkaller hit the following crash on >>> 7dfaa7bc99498da1c6c4a48bee8d2d5265161a8c >>> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master >>> compiler: gcc (GCC) 7.1.1 20170620 >>> .config is attached >>> Raw console output is attached. >>> >>> Unfortunately, I don't have any reproducer for this bug yet. >>> >> >> >> I guess this is more about kcmsock.c rather than workqueue.c. +kcm maintainers. > > > Looks like the work is not cancelled before being freed on this path. > Do you have a C reproducer for me to try? This is answered in the email text and the referenced link. If the wording is not clear, we should improve it. >>> ================================================================== >>> BUG: KASAN: use-after-free in worker_thread+0x15bb/0x1990 >>> kernel/workqueue.c:2245 >>> Read of size 8 at addr ffff8801c3a74110 by task kworker/u4:6/3515 >>> >>> CPU: 1 PID: 3515 Comm: kworker/u4:6 Not tainted 4.14.0-rc7+ #112 >>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >>> Google 01/01/2011 >>> Call Trace: >>> __dump_stack lib/dump_stack.c:17 [inline] >>> dump_stack+0x194/0x257 lib/dump_stack.c:53 >>> print_address_description+0x73/0x250 mm/kasan/report.c:252 >>> kasan_report_error mm/kasan/report.c:351 [inline] >>> kasan_report+0x25b/0x340 mm/kasan/report.c:409 >>> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 >>> worker_thread+0x15bb/0x1990 kernel/workqueue.c:2245 >>> kthread+0x35e/0x430 kernel/kthread.c:231 >>> ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:432 >>> >>> Allocated by task 31482: >>> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 >>> save_stack+0x43/0xd0 mm/kasan/kasan.c:447 >>> set_track mm/kasan/kasan.c:459 [inline] >>> kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 >>> kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 >>> kmem_cache_alloc+0x12e/0x760 mm/slab.c:3562 >>> kmem_cache_zalloc include/linux/slab.h:657 [inline] >>> kcm_attach net/kcm/kcmsock.c:1394 [inline] >>> kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline] >>> kcm_ioctl+0x2d1/0x1610 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:46 [inline] >>> do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 >>> SYSC_ioctl fs/ioctl.c:701 [inline] >>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 >>> entry_SYSCALL_64_fastpath+0x1f/0xbe >>> >>> Freed by task 1249: >>> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 >>> save_stack+0x43/0xd0 mm/kasan/kasan.c:447 >>> set_track mm/kasan/kasan.c:459 [inline] >>> kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 >>> __cache_free mm/slab.c:3504 [inline] >>> kmem_cache_free+0x77/0x280 mm/slab.c:3764 >>> unreserve_psock+0x5a1/0x780 net/kcm/kcmsock.c:547 >>> kcm_write_msgs+0xbae/0x1b80 net/kcm/kcmsock.c:590 >>> kcm_tx_work+0x2e/0x190 net/kcm/kcmsock.c:731 >>> process_one_work+0xbf0/0x1bc0 kernel/workqueue.c:2113 >>> worker_thread+0x223/0x1990 kernel/workqueue.c:2247 >>> kthread+0x35e/0x430 kernel/kthread.c:231 >>> ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:432 >>> >>> The buggy address belongs to the object at ffff8801c3a74040 >>> which belongs to the cache kcm_psock_cache of size 552 >>> The buggy address is located 208 bytes inside of >>> 552-byte region [ffff8801c3a74040, ffff8801c3a74268) >>> The buggy address belongs to the page: >>> page:ffffea00070e9d00 count:1 mapcount:0 mapping:ffff8801c3a74040 index:0x0 >>> compound_mapcount: 0 >>> flags: 0x2fffc0000008100(slab|head) >>> raw: 02fffc0000008100 ffff8801c3a74040 0000000000000000 000000010000000b >>> raw: ffffea00067920a0 ffff8801d3f39948 ffff8801d3f2a840 0000000000000000 >>> page dumped because: kasan: bad access detected >>> >>> Memory state around the buggy address: >>> ffff8801c3a74000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb >>> ffff8801c3a74080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>>> >>>> ffff8801c3a74100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> >>> ^ >>> ffff8801c3a74180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ffff8801c3a74200: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc >>> ================================================================== >>> >>> >>> --- >>> This bug is generated by a dumb bot. It may contain errors. >>> See https://goo.gl/tpsmEJ for details. >>> Direct all questions to syzkaller@googlegroups.com. >>> Please credit me with: Reported-by: syzbot >>> >>> syzbot will keep track of this bug report. >>> Once a fix for this bug is committed, please reply to this email with: >>> #syz fix: exact-commit-title >>> To mark this as a duplicate of another syzbot report, please reply with: >>> #syz dup: exact-subject-of-another-report >>> If it's a one-off invalid bug report, please reply with: >>> #syz invalid >>> Note: if the crash happens again, it will cause creation of a new bug >>> report. >>> Note: all commands must start from beginning of the line. >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "syzkaller-bugs" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to syzkaller-bugs+unsubscribe@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/syzkaller-bugs/001a114a7bc08e95e7055d783ea5%40google.com. >>> For more options, visit https://groups.google.com/d/optout.