netdev - [PATCH net] virtio: fix GSO with frames unaligned to size

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Message-Id: <20240725092203.26366-1-arefev@swemel.ru>
Date: Thu, 25 Jul 2024 12:22:03 +0300
From: Denis Arefev <arefev@...mel.ru>
To: kuba@...nel.org
Cc: arefev@...mel.ru,
	davem@...emloft.net,
	edumazet@...gle.com,
	eperezma@...hat.com,
	jasowang@...hat.com,
	linux-kselftest@...r.kernel.org,
	mst@...hat.com,
	netdev@...r.kernel.org,
	pabeni@...hat.com,
	shuah@...nel.org,
	virtualization@...ts.linux.dev,
	willemdebruijn.kernel@...il.com,
	xuanzhuo@...ux.alibaba.com
Subject: [PATCH net] virtio: fix GSO with frames unaligned to size

I checked the patch on three reproducers and all three DEFINITELY broke the core.

There are two malfunctions.

1. No flag skb_shinfo(skb)->tx_flags |= SKBFL_SHARED_FRAG;
 If it is not set then __skb_linearize will not be executed in skb_checksum_help.
 sk_buff remains fragmented (non-linear) and this is the first warning.
 OR add skb_shinfo(skb)->tx_flags |= SKBFL_SHARED_FRAG.
 OR ask Eric Dumazet (cef401de7be8c). Is checking if (skb_has_shared_frag(skb)) so important?
 in the skb_checksum_help function, is it enough if (skb_is_nonlinear(skb)) ?

2. The skb_segment algorithm and related checks, this is where you need time to think ...

Best regards Denis.