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From: Eric Dumazet <edumazet@google.com>
Date: Thu, 22 Feb 2024 14:27:18 +0100
Message-ID: <CANn89iJZnY_0iM8Ft9cAOA7twCb8iQ4jf5FJP8fubg9_Z0EZkg@mail.gmail.com>
Subject: Re: [syzbot] [net?] WARNING in mpls_gso_segment
To: Florian Westphal <fw@strlen.de>
Cc: syzbot <syzbot+99d15fcdb0132a1e1a82@syzkaller.appspotmail.com>, 
	davem@davemloft.net, dsahern@kernel.org, horms@kernel.org, kuba@kernel.org, 
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, 
	syzkaller-bugs@googlegroups.com
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On Thu, Feb 22, 2024 at 1:57=E2=80=AFPM Florian Westphal <fw@strlen.de> wro=
te:
>
> Eric Dumazet <edumazet@google.com> wrote:
> > I was thinking about adding a debug check in skb_inner_network_header(s=
kb)
> > if inner_network_header is zero (that would mean it is not 'set' yet),
> > but this would trigger even after your patch.
>
> What about adding:
>
> static inline bool skb_inner_network_header_was_set(const struct sk_buff =
*skb)
> {
>         return skb->inner_network_header > 0;
> }
>
> ... and using that instead of checking for negative header length
> post-subtraction?

SGTM