From: Xie He <xie.he.0141@gmail.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
syzbot <syzbot+4a2c52677a8a1aa283cb@syzkaller.appspotmail.com>,
William Tu <u9012063@gmail.com>,
Willem de Bruijn <willemb@google.com>
Subject: Re: [Patch net v3] ip_gre: set dev->hard_header_len and dev->needed_headroom properly
Date: Mon, 12 Oct 2020 18:56:32 -0700 [thread overview]
Message-ID: <CAJht_EPOjEACReo3M85TiKNquSPu92JWC3SfwsOr5PS7QDDqKw@mail.gmail.com> (raw)
In-Reply-To: <20201012231721.20374-1-xiyou.wangcong@gmail.com>
On Mon, Oct 12, 2020 at 4:17 PM Cong Wang <xiyou.wangcong@gmail.com> wrote:
>
> GRE tunnel has its own header_ops, ipgre_header_ops, and sets it
> conditionally. When it is set, it assumes the outer IP header is
> already created before ipgre_xmit().
>
> This is not true when we send packets through a raw packet socket,
> where L2 headers are supposed to be constructed by user. Packet
> socket calls dev_validate_header() to validate the header. But
> GRE tunnel does not set dev->hard_header_len, so that check can
> be simply bypassed, therefore uninit memory could be passed down
> to ipgre_xmit(). Similar for dev->needed_headroom.
>
> dev->hard_header_len is supposed to be the length of the header
> created by dev->header_ops->create(), so it should be used whenever
> header_ops is set, and dev->needed_headroom should be used when it
> is not set.
Acked-by: Xie He <xie.he.0141@gmail.com>
Thank you for your work, Cong!
next prev parent reply other threads:[~2020-10-13 2:42 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-12 23:17 [Patch net v3] ip_gre: set dev->hard_header_len and dev->needed_headroom properly Cong Wang
2020-10-13 1:46 ` Xie He
2020-10-13 1:56 ` Xie He [this message]
2020-10-14 1:38 ` Jakub Kicinski
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