netdev - Re: [syzbot] WARNING in __dev_change_net

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Thu, 11 Nov 2021 09:56:35 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Johannes Berg <johannes@...solutions.net>
Cc:     syzbot <syzbot+5434727aa485c3203fed@...kaller.appspotmail.com>,
        "andrii@...nel.org" <andrii@...nel.org>,
        "ast@...nel.org" <ast@...nel.org>,
        "avagin@...il.com" <avagin@...il.com>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "cong.wang@...edance.com" <cong.wang@...edance.com>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "hawk@...nel.org" <hawk@...nel.org>,
        "john.fastabend@...il.com" <john.fastabend@...il.com>,
        "kafai@...com" <kafai@...com>,
        "kpsingh@...nel.org" <kpsingh@...nel.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "songliubraving@...com" <songliubraving@...com>,
        "syzkaller-bugs@...glegroups.com" <syzkaller-bugs@...glegroups.com>,
        "yhs@...com" <yhs@...com>
Subject: Re: [syzbot] WARNING in __dev_change_net_namespace

On Thu, Nov 11, 2021 at 08:50:33AM +0100, Johannes Berg wrote:
> On Thu, 2021-11-11 at 06:43 +0000, syzbot wrote:
> > 
> > console output: https://syzkaller.appspot.com/x/log.txt?x=15b45fb6b00000
> 
> So we see that fault injection is triggering a memory allocation failure
> deep within the device_rename():
> 
> int __dev_change_net_namespace(struct net_device *dev, struct net *net,
>                                const char *pat, int new_ifindex)
> {
> ...
>         /* Fixup kobjects */
>         err = device_rename(&dev->dev, dev->name);
>         WARN_ON(err);
> 
> 
> So we hit that WARN_ON().
> 
> I'm not really sure what to do about that though. Feels like we should
> be able to cope with failures here, but clearly we don't, and it seems
> like it would also be tricky to do after all the work already done at
> this point.
> 
> Perhaps device_rename() could grow an API to preallocate all the
> memories, but that would also be fairly involved, I imagine?

That would be a mess to unwind at times.  For fault-injection stuff like
this, that can not be hit in "real world operation", if the issue can
not be easily handled, I don't think it is worth worrying about.

We have some things like this in the tty layer at boot time, if a memory
failure happens then, we have bigger overall problems in the system than
trying to recover from minor stuff like this.

thanks,

greg k-h