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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Thu, 13 Dec 2018 10:46:53 +0100
Message-ID: <CACT4Y+aw3rpLHprBdV2uqwtsy_m2NjwV2i0D56PJShSxNqV0rQ@mail.gmail.com>
Subject: Re: KASAN: use-after-free Read in tipc_group_cong
To:     Jon Maloy <jon.maloy@ericsson.com>
Cc:     syzbot+9845fed98688e01f431e@syzkaller.appspotmail.com,
        David Miller <davem@davemloft.net>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        tipc-discussion@lists.sourceforge.net,
        Ying Xue <ying.xue@windriver.com>
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On Thu, Dec 13, 2018 at 1:16 AM Jon Maloy <jon.maloy@ericsson.com> wrote:
> > -----Original Message-----
> > From: syzbot <syzbot+9845fed98688e01f431e@syzkaller.appspotmail.com>
> > Sent: 12-Dec-18 06:11
> > To: davem@davemloft.net; Jon Maloy <jon.maloy@ericsson.com>; linux-
> > kernel@vger.kernel.org; netdev@vger.kernel.org; syzkaller-
> > bugs@googlegroups.com; tipc-discussion@lists.sourceforge.net;
> > ying.xue@windriver.com
> > Subject: KASAN: use-after-free Read in tipc_group_cong
>
> This seems to be an effect of the same bug as reported in
> https://syzkaller.appspot.com/bug?extid=10a9db47c3a0e13eb31c

Let's do

#syz dup: KASAN: use-after-free Read in tipc_group_bc_cong

then.


> Cong posted a fix for that one. Did you see the crash after applying his patch?

Which patch do you mean? Unfortunately kernel development process is
so that it's not possible to figure out what fixes what.

I would just wait for new syzbot results.


> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    f5d582777bcb Merge branch 'for-linus' of git://git.kernel...
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1705d525400000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=c8970c89a0efbb23
> > dashboard link:
> > https://syzkaller.appspot.com/bug?extid=9845fed98688e01f431e
> > compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=101b6ba3400000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+9845fed98688e01f431e@syzkaller.appspotmail.com
> >
> > 8021q: adding VLAN 0 to HW filter on device team0
> > 8021q: adding VLAN 0 to HW filter on device team0
> > audit: type=1400 audit(1544592509.246:38): avc:  denied  { associate } for
> > pid=6204 comm="syz-executor5" name="syz5"
> > scontext=unconfined_u:object_r:unlabeled_t:s0
> > tcontext=system_u:object_r:unlabeled_t:s0 tclass=filesystem permissive=1
> > ==========================================================
> > ========
> > BUG: KASAN: use-after-free in tipc_group_find_dest net/tipc/group.c:255
> > [inline]
> > BUG: KASAN: use-after-free in tipc_group_cong+0x566/0x5d0
> > net/tipc/group.c:416
> > Read of size 8 at addr ffff8881c59f5000 by task syz-executor4/10565
> >
> > CPU: 1 PID: 10565 Comm: syz-executor4 Not tainted 4.20.0-rc6+ #151
> > Hardware name: Google Google Compute Engine/Google Compute Engine,
> > BIOS Google 01/01/2011 Call Trace:
> >   __dump_stack lib/dump_stack.c:77 [inline]
> >   dump_stack+0x244/0x39d lib/dump_stack.c:113
> >   print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
> >   kasan_report_error mm/kasan/report.c:354 [inline]
> >   kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
> >   __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
> >   tipc_group_find_dest net/tipc/group.c:255 [inline]
> >   tipc_group_cong+0x566/0x5d0 net/tipc/group.c:416
> >   tipc_send_group_anycast+0x9bb/0xc80 net/tipc/socket.c:972
> >   __tipc_sendmsg+0x12b1/0x1d40 net/tipc/socket.c:1309
> >   tipc_sendmsg+0x50/0x70 net/tipc/socket.c:1272
> >   sock_sendmsg_nosec net/socket.c:621 [inline]
> >   sock_sendmsg+0xd5/0x120 net/socket.c:631
> >   ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
> >   __sys_sendmsg+0x11d/0x280 net/socket.c:2154
> >   __do_sys_sendmsg net/socket.c:2163 [inline]
> >   __se_sys_sendmsg net/socket.c:2161 [inline]
> >   __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
> >   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> >   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > RIP: 0033:0x457679
> > Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83
> > cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > RSP: 002b:00007f813d748c78 EFLAGS: 00000246 ORIG_RAX:
> > 000000000000002e
> > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457679
> > RDX: 0000000000000000 RSI: 00000000200006c0 RDI: 0000000000000005
> > RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f813d7496d4
> > R13: 00000000004c44dd R14: 00000000004d74c8 R15: 00000000ffffffff
> >
> > Allocated by task 10551:
> >   save_stack+0x43/0xd0 mm/kasan/kasan.c:448
> >   set_track mm/kasan/kasan.c:460 [inline]
> >   kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
> >   kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
> >   kmalloc include/linux/slab.h:546 [inline]
> >   kzalloc include/linux/slab.h:741 [inline]
> >   tipc_group_create+0x152/0xa70 net/tipc/group.c:171
> >   tipc_sk_join net/tipc/socket.c:2829 [inline]
> >   tipc_setsockopt+0x2d1/0xd70 net/tipc/socket.c:2944
> >   __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
> >   __do_sys_setsockopt net/socket.c:1913 [inline]
> >   __se_sys_setsockopt net/socket.c:1910 [inline]
> >   __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
> >   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> >   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> >
> > Freed by task 10567:
> >   save_stack+0x43/0xd0 mm/kasan/kasan.c:448
> >   set_track mm/kasan/kasan.c:460 [inline]
> >   __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
> >   kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
> >   __cache_free mm/slab.c:3498 [inline]
> >   kfree+0xcf/0x230 mm/slab.c:3817
> >   tipc_group_delete+0x2e4/0x3f0 net/tipc/group.c:227
> >   tipc_sk_leave+0x113/0x220 net/tipc/socket.c:2863
> >   tipc_setsockopt+0x97d/0xd70 net/tipc/socket.c:2947
> >   __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
> >   __do_sys_setsockopt net/socket.c:1913 [inline]
> >   __se_sys_setsockopt net/socket.c:1910 [inline]
> >   __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
> >   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> >   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> >
> > The buggy address belongs to the object at ffff8881c59f5000
> >   which belongs to the cache kmalloc-192 of size 192 The buggy address is
> > located 0 bytes inside of
> >   192-byte region [ffff8881c59f5000, ffff8881c59f50c0) The buggy address
> > belongs to the page:
> > page:ffffea0007167d40 count:1 mapcount:0 mapping:ffff8881da800040
> > index:0x0
> > flags: 0x2fffc0000000200(slab)
> > raw: 02fffc0000000200 ffffea0007160488 ffffea00071aff08 ffff8881da800040
> > raw: 0000000000000000 ffff8881c59f5000 0000000100000010
> > 0000000000000000 page dumped because: kasan: bad access detected
> >
> > Memory state around the buggy address:
> >   ffff8881c59f4f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >   ffff8881c59f4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > > ffff8881c59f5000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >                     ^
> >   ffff8881c59f5080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> >   ffff8881c59f5100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > ==========================================================
> > ========
> >
> >
> > ---
> > This bug is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@googlegroups.com.
> >
> > syzbot will keep track of this bug report. See:
> > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> > syzbot.
> > syzbot can test patches for this bug, for details see:
> > https://goo.gl/tpsmEJ#testing-patches
>
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