linux-kernel - Re: [syzbot] KASAN: slab-out-of-bounds Read in copy

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Message-ID: <20211027031847-mutt-send-email-mst@kernel.org>
Date:   Wed, 27 Oct 2021 03:20:02 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Laurent Vivier <lvivier@...hat.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        syzbot <syzbot+b86736b5935e0d25b446@...kaller.appspotmail.com>,
        davem@...emloft.net, herbert@...dor.apana.org.au, jiri@...dia.com,
        kuba@...nel.org, leonro@...dia.com, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, mpm@...enic.com,
        netdev@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] KASAN: slab-out-of-bounds Read in copy_data

On Wed, Oct 27, 2021 at 09:08:04AM +0200, Laurent Vivier wrote:
> On 27/10/2021 00:34, Eric Dumazet wrote:
> > 
> > 
> > On 10/26/21 9:39 AM, syzbot wrote:
> > > Hello,
> > > 
> > > syzbot found the following issue on:
> > > 
> > > HEAD commit:    9ae1fbdeabd3 Add linux-next specific files for 20211025
> > > git tree:       linux-next
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=1331363cb00000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=aeb17e42bc109064
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=b86736b5935e0d25b446
> > > 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=116ce954b00000
> > > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=132fcf62b00000
> > > 
> > > The issue was bisected to:
> > > 
> > > commit 22849b5ea5952d853547cc5e0651f34a246b2a4f
> > > Author: Leon Romanovsky <leonro@...dia.com>
> > > Date:   Thu Oct 21 14:16:14 2021 +0000
> > > 
> > >      devlink: Remove not-executed trap policer notifications
> > 
> > More likely this came with
> > 
> > caaf2874ba27b92bca6f0298bf88bad94067ec37 hwrng: virtio - don't waste entropy
> > 
> 
> I'm going to have a look.
> 
> Thanks,
> Laurent

How bad is it if we just drop this and waste some bytes of entropy?

-- 
MST