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([2a0d:3344:2445:d510::f39]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4535ead202asm170467905e9.27.2025.06.24.03.02.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Jun 2025 03:02:50 -0700 (PDT) Message-ID: <5fb3c0e4-759c-4f56-8a78-e599c891f618@redhat.com> Date: Tue, 24 Jun 2025 12:02:48 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v2 1/2] virtio-net: xsk: rx: fix the frame's length check To: Bui Quang Minh , netdev@vger.kernel.org Cc: "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org References: <20250621144952.32469-1-minhquangbui99@gmail.com> <20250621144952.32469-2-minhquangbui99@gmail.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250621144952.32469-2-minhquangbui99@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/21/25 4:49 PM, Bui Quang Minh wrote: > When calling buf_to_xdp, the len argument is the frame data's length > without virtio header's length (vi->hdr_len). We check that len with > > xsk_pool_get_rx_frame_size() + vi->hdr_len > > to ensure the provided len does not larger than the allocated chunk > size. The additional vi->hdr_len is because in virtnet_add_recvbuf_xsk, > we use part of XDP_PACKET_HEADROOM for virtio header and ask the vhost > to start placing data from > > hard_start + XDP_PACKET_HEADROOM - vi->hdr_len > not > hard_start + XDP_PACKET_HEADROOM > > But the first buffer has virtio_header, so the maximum frame's length in > the first buffer can only be > > xsk_pool_get_rx_frame_size() > not > xsk_pool_get_rx_frame_size() + vi->hdr_len > > like in the current check. > > This commit adds an additional argument to buf_to_xdp differentiate > between the first buffer and other ones to correctly calculate the maximum > frame's length. > > Fixes: a4e7ba702701 ("virtio_net: xsk: rx: support recv small mode") It looks like the checks in the blamed commit above are correct and the bug has been added with commit 99c861b44eb1f ("virtio_net: xsk: rx: support recv merge mode")??? /P