From: Simon Horman <horms@kernel.org>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Xiang Mei <xmei5@asu.edu>,
andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com,
pabeni@redhat.com, netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org, jakub@cloudflare.com,
stable@vger.kernel.org, co+0ea1ac045375cf05@bugs.sh
Subject: Re: [PATCH net] vlan: require the MAC header to be present in __vlan_insert_inner_tag()
Date: Sun, 20 Sep 2026 10:26:57 +0100 [thread overview]
Message-ID: <20260920092657.GB13925@horms.kernel.org> (raw)
In-Reply-To: <20260919154911.642616cf@kernel.org>
On Sat, Sep 19, 2026 at 03:49:11PM -0700, Jakub Kicinski wrote:
> On Sat, 19 Sep 2026 08:45:35 +0100 Simon Horman wrote:
> > > + if (unlikely(!pskb_may_pull(skb, mac_len)))
> > > + return -EINVAL;
> > > +
> > > if (skb_cow_head(skb, meta_len + VLAN_HLEN) < 0)
> > > return -ENOMEM;
> >
> > TBH I am surprised that we have a bug like this in this function.
> > But your analysis matches my understanding of the code.
>
> FWIW I suspect it's because non-ethernet packets shouldn't normally
> reach ethernet helpers.
Yes, I agree that seems likely.
> But I'm not sure how practical it would be
> to push mac_len checks to the callers or anything of the sort,
> so we can as well check here..
next prev parent reply other threads:[~2026-09-20 9:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-15 8:31 [PATCH net] vlan: require the MAC header to be present in __vlan_insert_inner_tag() Xiang Mei
2026-09-19 7:45 ` Simon Horman
2026-09-19 22:49 ` Jakub Kicinski
2026-09-20 9:26 ` Simon Horman [this message]
2026-09-19 23:20 ` patchwork-bot+netdevbpf
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