netdev - Re: [PATCH bpf-next] bpf/verifier: properly clear union members after a ctx read

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Message-ID: <20180906053205.gziuwtxw6or6sxho@ast-mbp.dhcp.thefacebook.com>
Date:   Wed, 5 Sep 2018 22:32:07 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Edward Cree <ecree@...arflare.com>
Cc:     daniel@...earbox.net, ast@...nel.org, netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next] bpf/verifier: properly clear union members
 after a ctx read

On Wed, Sep 05, 2018 at 02:47:22PM +0100, Edward Cree wrote:
> On 05/09/18 03:23, Alexei Starovoitov wrote:
> > So would you agree it's fair to add
> > Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
> > ?
> Sure.  Though I don't think it needs backporting, as it's a conservative
>  bug (i.e. it merely prevents pruning, but that's safe security-wise).

agree. No backport necessary.

> > How about patch like the following:
> > ------------
> > From 422fd975ed78645ab67d2eb50ff6e1ff6fb3de32 Mon Sep 17 00:00:00 2001
> > From: Alexei Starovoitov <ast@...nel.org>
> > Date: Tue, 4 Sep 2018 19:13:44 -0700
> > Subject: [PATCH] bpf/verifier: fix verifier instability
> >
> > Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
> > Debugged-by: Edward Cree <ecree@...arflare.com> 
> > Signed-off-by: Alexei Starovoitov <ast@...nel.org>
> Acked-by: Edward Cree <ecree@...arflare.com>

Thanks. I copy-pasted your commit log and pushed to bpf-next.

Much appreciate the time and effort spent on root causing these issues.