From: Tadeusz Struk <tadeusz.struk@linaro.org>
To: David Ahern <dsahern@kernel.org>,
David Laight <David.Laight@ACULAB.COM>,
"davem@davemloft.net" <davem@davemloft.net>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.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 11:46:07 -0800 [thread overview]
Message-ID: <45522c89-a3b4-4b98-232b-9c69470124a3@linaro.org> (raw)
In-Reply-To: <66463e26-8564-9f58-ce41-9a2843891d1a@kernel.org>
On 3/8/22 10:18, David Ahern wrote:
>> alloclen = 1480
>> alloc_extra = 136
>> datalen = 64095
>> fragheaderlen = 1480
>> fraglen = 65575
>> transhdrlen = 0
>> mtu = 1480
>>
> Does this solve the problem (whitespace damaged on paste, but it is just
> a code move and removing fraglen getting set twice):
>
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index e69fac576970..59f036241f1b 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -1589,6 +1589,15 @@ static int __ip6_append_data(struct sock *sk,
>
> if (datalen > (cork->length <= mtu &&
> !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
> datalen = maxfraglen - fragheaderlen -
> rt->dst.trailer_len;
> +
> + if (datalen != length + fraggap) {
> + /*
> + * this is not the last fragment, the
> trailer
> + * space is regarded as data space.
> + */
> + datalen += rt->dst.trailer_len;
> + }
> +
> fraglen = datalen + fragheaderlen;
> pagedlen = 0;
>
> @@ -1615,16 +1624,6 @@ static int __ip6_append_data(struct sock *sk,
> }
> alloclen += alloc_extra;
>
> - if (datalen != length + fraggap) {
> - /*
> - * this is not the last fragment, the
> trailer
> - * space is regarded as data space.
> - */
> - datalen += rt->dst.trailer_len;
> - }
> -
> - fraglen = datalen + fragheaderlen;
> -
> copy = datalen - transhdrlen - fraggap - pagedlen;
> if (copy < 0) {
> err = -EINVAL;
That fails in the same way:
skbuff: skb_over_panic: text:ffffffff83e7b48b len:65575 put:65575
head:ffff888101f8a000 data:ffff888101f8a088 tail:0x100af end:0x6c0 dev:<NULL>
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:113!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 1852 Comm: repro Not tainted 5.17.0-rc7-00020-gea4424be1688-dirty #19
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1.fc35
RIP: 0010:skb_panic+0x173/0x175
I'm not sure how it supposed to help since it doesn't change the alloclen at all.
I think the problem here is that the size of the allocated skb is too small.
--
Thanks,
Tadeusz
next prev parent reply other threads:[~2022-03-08 19:46 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 [this message]
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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