kernel panic: stack is corrupted in lock_release

[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=11217f3b400000
kernel config: https://syzkaller.appspot.com/x/.config?x=76d28549be7c27cf
dashboard link: https://syzkaller.appspot.com/bug?extid=bc3cd5b4c1f71fc3c65d
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: []

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+bc3cd5...@syzkaller.appspotmail.com

binder: 15146:15152 ioctl c0306201 0 returned -14
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in:
lock_release+0x98e/0xc40 kernel/locking/lockdep.c:3864
CPU: 0 PID: 15166 Comm: syz-executor4 Not tainted 4.20.0+ #1
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 2:01 PM syzbot
<syzbot+bc3cd5...@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=11217f3b400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=76d28549be7c27cf
> dashboard link: https://syzkaller.appspot.com/bug?extid=bc3cd5b4c1f71fc3c65d
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> CC: []
>
> 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+bc3cd5...@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