Re: [syzbot] upstream build error (17)

[Dmitry Vyukov]

On Wed, 6 Apr 2022 at 20:26, Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote:
>
> On Wed, Apr 6, 2022 at 10:33 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
> >
> > On 4/6/22 18:20, syzbot wrote:
> > > Hello,
> > >
> > > syzbot found the following issue on:
> > >
> > > HEAD commit:    3e732ebf7316 Merge tag 'for_linus' of git://git.kernel.org..
> > > git tree:       upstream
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=10ca0687700000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=eba855fbe3373b4f
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=6b36bab98e240873fd5a
> > > compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
> > >
> > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > Reported-by: syzbot+6b36bab98e240873fd5a@xxxxxxxxxxxxxxxxxxxxxxxxx
> > >
> > > arch/x86/kvm/emulate.c:3332:5: error: stack frame size (2552) exceeds limit (2048) in function 'emulator_task_switch' [-Werror,-Wframe-larger-than]
> > > drivers/block/loop.c:1524:12: error: stack frame size (2648) exceeds limit (2048) in function 'lo_ioctl' [-Werror,-Wframe-larger-than]
> >
> > I spot-checked these two and the stack frame is just 144 and 320 bytes
> > respectively on a normal compile.  This is probably just the effect of
> > some of the sanitizer options.
>
> Yep.
> $ wget -q https://syzkaller.appspot.com/x/.config\?x\=eba855fbe3373b4f
> -O - | grep CONFIG_KASAN=y
> CONFIG_KASAN=y
> https://github.com/ClangBuiltLinux/linux/issues/39 (our oldest still-open issue)


The issue is due to:

commit b9080ba4a6ec56447f263082825a4fddb873316b
Date:   Wed Mar 23 12:21:10 2022 +0100
    x86/defconfig: Enable WERROR

Marco has disabled it in syzbot configs:
https://github.com/google/syzkaller/commit/53c67432e69b0df4ff64448b944cbffaecec20f4

#syz invalid