Message-ID: <CAM_iQpW1uto7JadprhHgrgyL59bLCZXArW=4WY_smGPSfgdqVw@mail.gmail.com>
Date:   Mon, 20 Aug 2018 22:29:55 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     syzbot+b9c8f3ab2994b7cd1625@...kaller.appspotmail.com
Cc:     David Miller <davem@...emloft.net>,
        Jon Maloy <jon.maloy@...csson.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        syzkaller-bugs@...glegroups.com,
        tipc-discussion@...ts.sourceforge.net,
        Ying Xue <ying.xue@...driver.com>
Subject: Re: KASAN: use-after-free Read in tipc_group_fill_sock_diag

On Sat, Aug 18, 2018 at 5:10 PM syzbot
<syzbot+b9c8f3ab2994b7cd1625@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    a18d783fedfe Merge tag 'driver-core-4.19-rc1' of git://git..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14bcc936400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=7eeabb17332898c0
> dashboard link: https://syzkaller.appspot.com/bug?extid=b9c8f3ab2994b7cd1625
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=1374ec4a400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+b9c8f3ab2994b7cd1625@...kaller.appspotmail.com
>
> IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
> IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
> IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
> 8021q: adding VLAN 0 to HW filter on device team0
> ==================================================================
> BUG: KASAN: use-after-free in tipc_group_fill_sock_diag+0x7b9/0x84b
> net/tipc/group.c:921
> Read of size 4 at addr ffff8801ceb5565c by task syz-executor0/4838
>
> CPU: 1 PID: 4838 Comm: syz-executor0 Not tainted 4.18.0+ #196
> 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+0x1c9/0x2b4 lib/dump_stack.c:113
>   print_address_description+0x6c/0x20b mm/kasan/report.c:256
>   kasan_report_error mm/kasan/report.c:354 [inline]
>   kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
>   __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
>   tipc_group_fill_sock_diag+0x7b9/0x84b net/tipc/group.c:921
>   tipc_sk_fill_sock_diag+0x9f8/0xdb0 net/tipc/socket.c:3322
>   __tipc_add_sock_diag+0x22f/0x360 net/tipc/diag.c:62
>   tipc_nl_sk_walk+0x68d/0xd30 net/tipc/socket.c:3249
>   tipc_diag_dump+0x24/0x30 net/tipc/diag.c:73


Seems we need just unlink the tipc sock before deleting group,
otherwise probably have to take a refcnt of group.

For example, moving tipc_sk_leave() down after tipc_sk_remove()?


--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -571,10 +571,10 @@ static int tipc_release(struct socket *sock)

        __tipc_shutdown(sock, TIPC_ERR_NO_PORT);
        sk->sk_shutdown = SHUTDOWN_MASK;
-       tipc_sk_leave(tsk);
        tipc_sk_withdraw(tsk, 0, NULL);
        sk_stop_timer(sk, &sk->sk_timer);
        tipc_sk_remove(tsk);
+       tipc_sk_leave(tsk);

        /* Reject any messages that accumulated in backlog queue */
        release_sock(sk);




>   netlink_dump+0x519/0xd50 net/netlink/af_netlink.c:2233
>   __netlink_dump_start+0x4f1/0x6f0 net/netlink/af_netlink.c:2329
>   netlink_dump_start include/linux/netlink.h:213 [inline]
>   tipc_sock_diag_handler_dump+0x234/0x340 net/tipc/diag.c:89
>   __sock_diag_cmd net/core/sock_diag.c:232 [inline]
>   sock_diag_rcv_msg+0x31d/0x410 net/core/sock_diag.c:263
>   netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2454
>   sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:274
>   netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
>   netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1343
>   netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1908
>   sock_sendmsg_nosec net/socket.c:621 [inline]
>   sock_sendmsg+0xd5/0x120 net/socket.c:631
>   ___sys_sendmsg+0x7fd/0x930 net/socket.c:2114
>   __sys_sendmsg+0x11d/0x290 net/socket.c:2152
>   __do_sys_sendmsg net/socket.c:2161 [inline]
>   __se_sys_sendmsg net/socket.c:2159 [inline]
>   __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2159
>   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x457089
> Code: fd b4 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 b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f3a5d506c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007f3a5d5076d4 RCX: 0000000000457089
> RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000006
> RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 00000000004d4088 R14: 00000000004c8ab0 R15: 0000000000000000
>
> Allocated by task 4838:
>   save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>   set_track mm/kasan/kasan.c:460 [inline]
>   kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
>   kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
>   kmalloc include/linux/slab.h:513 [inline]
>   kzalloc include/linux/slab.h:707 [inline]
>   tipc_group_create+0x155/0xa70 net/tipc/group.c:171
>   tipc_sk_join net/tipc/socket.c:2766 [inline]
>   tipc_setsockopt+0x2d1/0xd70 net/tipc/socket.c:2881
>   __sys_setsockopt+0x1c5/0x3b0 net/socket.c:1900
>   __do_sys_setsockopt net/socket.c:1911 [inline]
>   __se_sys_setsockopt net/socket.c:1908 [inline]
>   __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1908
>   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Freed by task 4837:
>   save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>   set_track mm/kasan/kasan.c:460 [inline]
>   __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
>   kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
>   __cache_free mm/slab.c:3498 [inline]
>   kfree+0xd9/0x260 mm/slab.c:3813
>   tipc_group_delete+0x2e5/0x3f0 net/tipc/group.c:227
>   tipc_sk_leave+0x113/0x220 net/tipc/socket.c:2800
>   tipc_release+0x14e/0x12b0 net/tipc/socket.c:574
>   __sock_release+0xd7/0x250 net/socket.c:579
>   sock_close+0x19/0x20 net/socket.c:1139
>   __fput+0x39b/0x860 fs/file_table.c:251
>   ____fput+0x15/0x20 fs/file_table.c:282
>   task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
>   tracehook_notify_resume include/linux/tracehook.h:193 [inline]
>   exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
>   prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
>   syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
>   do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> The buggy address belongs to the object at ffff8801ceb55600
>   which belongs to the cache kmalloc-192 of size 192
> The buggy address is located 92 bytes inside of
>   192-byte region [ffff8801ceb55600, ffff8801ceb556c0)
> The buggy address belongs to the page:
> page:ffffea00073ad540 count:1 mapcount:0 mapping:ffff8801dac00040 index:0x0
> flags: 0x2fffc0000000100(slab)
> raw: 02fffc0000000100 ffffea00073a5088 ffffea00073ae5c8 ffff8801dac00040
> raw: 0000000000000000 ffff8801ceb55000 0000000100000010 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>   ffff8801ceb55500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   ffff8801ceb55580: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > ffff8801ceb55600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                                      ^
>   ffff8801ceb55680: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>   ffff8801ceb55700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> ---
> 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@...glegroups.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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