netdev - Re: [PATCH bpf 0/2] Two bpf fixes

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Message-ID: <20180615193143.6dyizhdq345lgwf2@ast-mbp.dhcp.thefacebook.com>
Date:   Fri, 15 Jun 2018 12:31:45 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     ast@...nel.org, netdev@...r.kernel.org
Subject: Re: [PATCH bpf 0/2] Two bpf fixes

On Fri, Jun 15, 2018 at 02:30:46AM +0200, Daniel Borkmann wrote:
> First one is a panic I ran into while testing the second
> one where we got several syzkaller reports. Series here
> fixes both.
> 
> Thanks!

Applied, thanks.

The second patch looks dubious to me though.
Nothing in the kernel tree checks the return value of set_memory_ro()
and my understanding that it can fail only when part of huge page
is being marked and pages have to be split. In bpf case I don't think
it's ever the case, so the patch is silencing purely theoretical
syzbot splat that can happen with artificial error injection.
I bet we're still going to see this splat in set_memory_rw.
imo the better fix would have been to drop WARN_ON from both.