From: Tadeusz Struk <tadeusz.struk@linaro.org>
To: David Laight <David.Laight@ACULAB.COM>,
"davem@davemloft.net" <davem@davemloft.net>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
David Ahern <dsahern@kernel.org>,
Jakub Kicinski <kuba@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" <netdev@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
"syzbot+e223cf47ec8ae183f2a0@syzkaller.appspotmail.com"
<syzbot+e223cf47ec8ae183f2a0@syzkaller.appspotmail.com>
Subject: Re: [PATCH] net: ipv6: fix invalid alloclen in __ip6_append_data
Date: Tue, 8 Mar 2022 07:43:25 -0800 [thread overview]
Message-ID: <6155b68c-161b-0745-b303-f7e037b56e28@linaro.org> (raw)
In-Reply-To: <14626165dad64bbaabed58ba7d59e523@AcuMS.aculab.com>
Hi David,
On 3/7/22 18:58, David Laight wrote:
>> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
>> index 4788f6b37053..622345af323e 100644
>> --- a/net/ipv6/ip6_output.c
>> +++ b/net/ipv6/ip6_output.c
>> @@ -1629,6 +1629,13 @@ static int __ip6_append_data(struct sock *sk,
>> err = -EINVAL;
>> goto error;
>> }
>> + if (unlikely(alloclen < fraglen)) {
>> + if (printk_ratelimit())
>> + pr_warn("%s: wrong alloclen: %d, fraglen: %d",
>> + __func__, alloclen, fraglen);
>> + alloclen = fraglen;
>> + }
>> +
> Except that is a valid case, see a few lines higher:
>
> alloclen = min_t(int, fraglen, MAX_HEADER);
> pagedlen = fraglen - alloclen;
>
> You need to report the input values that cause the problem later on.
OK, but in this case it falls into the first if block:
https://elixir.bootlin.com/linux/v5.17-rc7/source/net/ipv6/ip6_output.c#L1606
where alloclen is assigned the value of mtu.
The values in this case are just before the alloc_skb() are:
alloclen = 1480
alloc_extra = 136
datalen = 64095
fragheaderlen = 1480
fraglen = 65575
transhdrlen = 0
mtu = 1480
--
Thanks,
Tadeusz
next prev parent reply other threads:[~2022-03-08 15:43 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 [this message]
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
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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