kernel panic: stack is corrupted in ktime_get

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 195303136f19 Merge tag 'kconfig-v4.21-2' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=153db700c00000
kernel config: https://syzkaller.appspot.com/x/.config?x=5e7dc790609552d7
dashboard link: https://syzkaller.appspot.com/bug?extid=75a9e761b5b933794abd
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
CC: [john....@linaro.org linux-...@vger.kernel.org
sb...@kernel.org tg...@linutronix.de]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+75a9e7...@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): hsr0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
8021q: adding VLAN 0 to HW filter on device batadv0
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in:
ktime_get+0x3f2/0x400 kernel/time/timekeeping.c:758
CPU: 0 PID: 18795 Comm: syz-executor4 Not tainted 4.20.0+ #175
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[Dmitry Vyukov]

On Wed, Jan 2, 2019 at 11:41 AM syzbot
<syzbot+75a9e7...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 195303136f19 Merge tag 'kconfig-v4.21-2' of git://git.kern..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=153db700c00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=5e7dc790609552d7
> dashboard link: https://syzkaller.appspot.com/bug?extid=75a9e761b5b933794abd
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
> CC: [john....@linaro.org linux-...@vger.kernel.org
> sb...@kernel.org tg...@linutronix.de]
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+75a9e7...@syzkaller.appspotmail.com

Presumably a random manifestation of the stack overflow/corruption:

#syz dup: kernel panic: stack is corrupted in udp4_lib_lookup2

See https://groups.google.com/forum/#!msg/syzkaller-bugs/vr87kmG5qRI/31nOcuVsFgAJ

> IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
> IPv6: ADDRCONF(NETDEV_UP): hsr0: link is not ready
> IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
> IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
> 8021q: adding VLAN 0 to HW filter on device batadv0
> Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in:
> ktime_get+0x3f2/0x400 kernel/time/timekeeping.c:758
> CPU: 0 PID: 18795 Comm: syz-executor4 Not tainted 4.20.0+ #175
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> ---
> 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 syzk...@googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> syzbot.
>

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