From: Fred Li <dracodingfly@gmail•com>
To: pabeni@redhat•com
Cc: aleksander.lobakin@intel•com, andrii@kernel•org, ast@kernel•org,
bpf@vger•kernel.org, daniel@iogearbox•net, davem@davemloft•net,
dracodingfly@gmail•com, edumazet@google•com, haoluo@google•com,
hawk@kernel•org, john.fastabend@gmail•com, jolsa@kernel•org,
kpsingh@kernel•org, kuba@kernel•org,
linux-kernel@vger•kernel.org, linux@weissschuh•net,
martin.lau@linux•dev, mkhalfella@purestorage•com, nbd@nbd•name,
netdev@vger•kernel.org, sashal@kernel•org, sdf@google•com,
song@kernel•org, yonghong.song@linux•dev,
herbert@gondor•apana.org.au
Subject: Re: [PATCH v2 1/2] net: Fix skb_segment when splitting gso_size mangled skb having linear-headed frag_list whose head_frag=true
Date: Wed, 3 Jul 2024 20:21:53 +0800 [thread overview]
Message-ID: <20240703122153.25381-1-dracodingfly@gmail.com> (raw)
In-Reply-To: <fd44c91884d0ebf3625ac85a1049679a987f8f79.camel@redhat.com>
> I must admit I more than a bit lost in the many turns of skb_segment(),
> but the above does not look like the correct solution, as it will make
> the later BUG_ON() unreachable/meaningless.
Sorry, the subsequent BUG_ON maybe should be removed in this patch, because
for skb_headlen(list_skb) > len, it will continue splitting as commit 13acc94eff122
(net: permit skb_segment on head_frag frag_list skb) does.
>
> Do I read correctly that when the BUG_ON() triggers:
>
> list_skb->len is 125
> len is 75
> list_skb->frag_head is true
>
yes, it's correct.
list_skb->len is 125
gso_size is 75, also the len in the BUG_ON conditon
list_skb->head_frag is true
> It looks like skb_segment() is becoming even and ever more complex to
> cope with unexpected skb layouts, only possibly when skb_segment() is
> called by some BPF helpers.
>
> Thanks,
>
> Paolo
I'll wait for more suggestions from others.
Thanks
Fred Li
next prev parent reply other threads:[~2024-07-03 12:22 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-26 6:55 [PATCH v2 2/2] test_bpf: Introduce an skb_segment test for frag_list whose head_frag=true and gso_size was mangled Fred Li
2024-06-26 6:55 ` [PATCH v2 1/2] net: Fix skb_segment when splitting gso_size mangled skb having linear-headed frag_list whose head_frag=true Fred Li
2024-07-02 9:23 ` Paolo Abeni
2024-07-03 12:21 ` Fred Li [this message]
2024-07-06 14:26 ` Willem de Bruijn
2024-07-08 14:31 ` [PATCH] net: linearizing skb when downgrade gso_size Fred Li
2024-07-09 15:53 ` Willem de Bruijn
2024-07-09 20:16 ` Herbert Xu
2024-07-09 21:29 ` Willem de Bruijn
2024-07-10 23:06 ` Herbert Xu
2024-07-12 8:17 ` Fred Li
2024-07-17 5:35 ` [PATCH v3] " Fred Li
2024-07-17 16:32 ` Willem de Bruijn
2024-07-18 7:42 ` Fred Li
2024-07-19 2:46 ` [PATCH v4] bpf: Fixed a segment issue " Fred Li
2024-07-19 18:22 ` Willem de Bruijn
2024-07-22 3:08 ` [PATCH bpf v5] bpf: Fixed " Fred Li
2024-07-22 16:29 ` Willem de Bruijn
2024-07-24 13:37 ` Fred Li
2024-07-25 10:09 ` Daniel Borkmann
2024-06-26 6:55 ` [PATCH v2 0/2] net: Fix BUG_ON for segment frag_list with mangled gso_size and head_frag is true Fred Li
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