From: Shmulik Ladkani <shmulik.ladkani@gmail.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
Eric Dumazet <eric.dumazet@gmail.com>,
netdev <netdev@vger.kernel.org>,
Alexander Duyck <alexander.duyck@gmail.com>,
Alexei Starovoitov <ast@kernel.org>, Yonghong Song <yhs@fb.com>,
Steffen Klassert <steffen.klassert@secunet.com>,
Shmulik Ladkani <shmulik@metanetworks.com>,
eyal@metanetworks.com
Subject: Re: BUG_ON in skb_segment, after bpf_skb_change_proto was applied
Date: Mon, 2 Sep 2019 16:44:44 +0300 [thread overview]
Message-ID: <20190902164444.00f32685@pixies> (raw)
In-Reply-To: <CA+FuTSfVsgNDi7c=GUU8nMg2hWxF2SjCNLXetHeVPdnxAW5K-w@mail.gmail.com>
On Sun, 1 Sep 2019 16:05:48 -0400
Willem de Bruijn <willemdebruijn.kernel@gmail.com> wrote:
> One quick fix is to disable sg and thus revert to copying in this
> case. Not ideal, but better than a kernel splat:
>
> @@ -3714,6 +3714,9 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
> sg = !!(features & NETIF_F_SG);
> csum = !!can_checksum_protocol(features, proto);
>
> + if (list_skb && skb_headlen(list_skb) && !list_skb->head_frag)
> + sg = false;
> +
Many thanks Willem for looking into this.
Indeed the above suggestion avoids the splat, at least with the
reproducer.
I'll look deeper into this, to make sure the generated skbs are indeed
legit and have correct content.
Shmulik
next prev parent reply other threads:[~2019-09-02 13:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-26 14:07 BUG_ON in skb_segment, after bpf_skb_change_proto was applied Shmulik Ladkani
2019-08-26 17:47 ` Eric Dumazet
2019-08-27 11:42 ` Shmulik Ladkani
2019-08-27 12:10 ` Daniel Borkmann
2019-08-28 5:56 ` Shmulik Ladkani
2019-08-29 12:22 ` Shmulik Ladkani
2019-09-01 20:05 ` Willem de Bruijn
2019-09-02 13:44 ` Shmulik Ladkani [this message]
2019-09-03 15:51 ` Shmulik Ladkani
2019-09-03 16:23 ` Willem de Bruijn
2019-09-03 17:03 ` Shmulik Ladkani
2019-09-03 17:24 ` Willem de Bruijn
2019-08-27 15:09 ` Eric Dumazet
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