From: Eric Dumazet <eric.dumazet@gmail.com>
To: Phi Nguyen <phind.uet@gmail.com>, Eric Dumazet <edumazet@google.com>
Cc: "Song Liu" <songliubraving@fb.com>,
"Alexander Lobakin" <alobakin@pm.me>,
syzbot+989efe781c74de1ddb54@syzkaller.appspotmail.com,
"Alexei Starovoitov" <ast@kernel.org>,
"Wei Wang" <weiwan@google.com>,
"Mahesh Bandewar" <maheshb@google.com>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"John Fastabend" <john.fastabend@gmail.com>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Yonghong Song" <yhs@fb.com>,
linux-kernel-mentees@lists.linuxfoundation.org,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
kpsingh@kernel.org, memxor@gmail.com,
"Jakub Kicinski" <kuba@kernel.org>,
netdev <netdev@vger.kernel.org>,
"Antoine Tenart" <atenart@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"David Miller" <davem@davemloft.net>,
"Björn Töpel" <bjorn@kernel.org>, bpf <bpf@vger.kernel.org>,
"Martin KaFai Lau" <kafai@fb.com>,
"Taehee Yoo" <ap420073@gmail.com>
Subject: Re: [PATCH] net: drop skbs in napi->rx_list when removing the napi context.
Date: Fri, 13 Aug 2021 12:16:34 +0200 [thread overview]
Message-ID: <8f324e46-f05c-42d7-9599-a43de7be17dc@gmail.com> (raw)
In-Reply-To: <663ac8c4-b0c3-5af6-c3c3-f371e0410a43@gmail.com>
On 8/12/21 9:17 PM, Phi Nguyen wrote:
> On 8/12/2021 3:07 PM, Eric Dumazet wrote:
>> Also I object to this fix.
>>
>> If packets have been stored temporarily in GRO, they should be
>> released at some point,
>> normally at the end of a napi poll.
>>
>> By released, I mean that these packets should reach the upper stack,
>> instead of being dropped without
>> any notification.
>>
>> It seems a call to gro_normal_list() is missing somewhere.
>>
>> Can you find where ?
>>
>> Thanks !
>> H Eric,
>
> I think the location that should have a call to gro_normal_list() is __netif_napi_del(). Let say, if the driver call a function that lead to gro_normal_one(), and add a skb to the rx_list while the napi poll is not scheduled, and the driver remove the napi context before a napi poll could be triggered, then the added skb will be lost.
>
> Actually, this was the first solution that I tried with syzbot (It passed the test too).
> Best regards,
> Phi
I think the real bug is in drivers/net/tun.c
It can call napi_gro_frags() and I do not see corresponding napi_complete()
This seems completely bogus.
Your patch only works around one the many bugs caused by
commit 90e33d45940793def6f773b2d528e9f3c84ffdc7 tun: enable napi_gro_frags() for TUN/TAP driver
I suggest not adding your patch, because we should fix the root cause.
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next prev parent reply other threads:[~2021-08-13 10:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-11 23:59 [PATCH] net: drop skbs in napi->rx_list when removing the napi context Nguyen Dinh Phi
2021-08-12 4:50 ` Hillf Danton
2021-08-12 5:19 ` [syzbot] memory leak in packet_sendmsg syzbot
2021-08-12 7:07 ` [PATCH] net: drop skbs in napi->rx_list when removing the napi context Eric Dumazet via Linux-kernel-mentees
2021-08-12 19:17 ` Phi Nguyen
2021-08-13 10:16 ` Eric Dumazet [this message]
2021-08-13 10:51 ` Nguyen Dinh Phi
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