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From: Tadeusz Struk <tadeusz.struk@linaro.org>
To: Jakub Kicinski <kuba@kernel.org>
Cc: davem@davemloft.net,
	Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	David Ahern <dsahern@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	syzbot+e223cf47ec8ae183f2a0@syzkaller.appspotmail.com
Subject: Re: [PATCH v2] net: ipv6: fix skb_over_panic in __ip6_append_data
Date: Thu, 10 Mar 2022 14:42:29 -0800	[thread overview]
Message-ID: <62a9b061-1cf5-dff1-c062-a3961de92dca@linaro.org> (raw)
In-Reply-To: <20220310143011.00c21f53@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>

On 3/10/22 14:30, Jakub Kicinski wrote:
>> +
>> +			/*
>> +			 *	Check if there is still room for payload
>> +			 */
> TBH I think the check is self-explanatory. Not worth a banner comment,
> for sure.

Ok

> 
>> +			if (fragheaderlen >= mtu) {
>> +				err = -EMSGSIZE;
>> +				kfree_skb(skb);
>> +				goto error;
>> +			}
> Not sure if Willem prefers this placement, but seems like we can lift
> this check out of the loop, as soon as fragheaderlen and mtu are known.
> 

He said to check it before the skb_put() and so I did.
The fragheaderlen is known early, but mtu can be updated inside the loop
by ip6_append_data_mtu() so I'm not sure we can do the check before that.

-- 
Thanks,
Tadeusz

  reply	other threads:[~2022-03-10 22:42 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-08  0:01 [PATCH] net: ipv6: fix invalid alloclen in __ip6_append_data Tadeusz Struk
2022-03-08  2:58 ` David Laight
2022-03-08 15:43   ` Tadeusz Struk
2022-03-08 18:18     ` David Ahern
2022-03-08 19:46       ` Tadeusz Struk
2022-03-09  5:01         ` David Ahern
2022-03-09 21:37           ` Tadeusz Struk
2022-03-10 14:39             ` Willem de Bruijn
2022-03-10 16:06               ` Tadeusz Struk
2022-03-10 17:32                 ` Willem de Bruijn
2022-03-10 21:14                   ` Tadeusz Struk
2022-03-10 22:13                   ` [PATCH v2] net: ipv6: fix skb_over_panic " Tadeusz Struk
2022-03-10 22:18                     ` David Laight
2022-03-10 22:30                     ` Jakub Kicinski
2022-03-10 22:42                       ` Tadeusz Struk [this message]
2022-03-10 22:43                       ` Willem de Bruijn
2022-03-10 23:04                         ` Tadeusz Struk
2022-03-10 23:05                         ` David Laight
2022-03-10 23:25                         ` [PATCH v3] " Tadeusz Struk
2022-03-11  1:49                           ` Willem de Bruijn
2022-03-11  3:43                             ` Tadeusz Struk
2022-03-12  1:40                           ` patchwork-bot+netdevbpf

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