Re: [syzbot] WARNING in component_del

[Pavel Skripkin]

Hi Daniel,

On 2/8/22 15:30, Daniel Vetter wrote:
> On Mon, Feb 07, 2022 at 11:51:29PM -0800, syzbot wrote:
> > syzbot has found a reproducer for the following issue on:
> >
> > HEAD commit:    555f3d7be91a Merge tag '5.17-rc3-ksmbd-server-fixes' of gi..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=130a0c2c700000

(*)

> > kernel config:  https://syzkaller.appspot.com/x/.config?x=266de9da75c71a45
> > dashboard link: https://syzkaller.appspot.com/bug?extid=60df062e1c41940cae0f
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15880d84700000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14de0c77b00000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+60df062e1c41940cae0f@xxxxxxxxxxxxxxxxxxxxxxxxx
>
>  From a quick grep usb seems to have indeed gained some component code, and
> I'm not aware of any drm usb drivers using component. So I think this is
> an usb issue, not a drm one.

It looks like missing error handling. syzbot injected allocation failure 
inside component_add(), but usb_hub_create_port_device() just prints 
warn message in case of component_add() failure (see log (*))

And then calling component_del() on non-added item causes WARN_ON()

Can't prove my thoughts, since there is no repro :(




With regards,
Pavel Skripkin