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Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Bui Quang Minh Subject: [PATCH net v2 1/2] virtio-net: xsk: rx: fix the frame's length check Date: Sat, 21 Jun 2025 21:49:51 +0700 Message-ID: <20250621144952.32469-2-minhquangbui99@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250621144952.32469-1-minhquangbui99@gmail.com> References: <20250621144952.32469-1-minhquangbui99@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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") Signed-off-by: Bui Quang Minh Reviewed-by: Xuan Zhuo --- drivers/net/virtio_net.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index e53ba600605a..1eb237cd5d0b 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1127,15 +1127,29 @@ static void check_sq_full_and_disable(struct virtne= t_info *vi, } } =20 +/* Note that @len is the length of received data without virtio header */ static struct xdp_buff *buf_to_xdp(struct virtnet_info *vi, - struct receive_queue *rq, void *buf, u32 len) + struct receive_queue *rq, void *buf, + u32 len, bool first_buf) { struct xdp_buff *xdp; u32 bufsize; =20 xdp =3D (struct xdp_buff *)buf; =20 - bufsize =3D xsk_pool_get_rx_frame_size(rq->xsk_pool) + vi->hdr_len; + /* In virtnet_add_recvbuf_xsk, we use part of XDP_PACKET_HEADROOM for + * virtio header and ask the vhost to fill data from + * hard_start + XDP_PACKET_HEADROOM - vi->hdr_len + * The first buffer has virtio header so the remaining region for frame + * data is + * xsk_pool_get_rx_frame_size() + * While other buffers than the first one do not have virtio header, so + * the maximum frame data's length can be + * xsk_pool_get_rx_frame_size() + vi->hdr_len + */ + bufsize =3D xsk_pool_get_rx_frame_size(rq->xsk_pool); + if (!first_buf) + bufsize +=3D vi->hdr_len; =20 if (unlikely(len > bufsize)) { pr_debug("%s: rx error: len %u exceeds truesize %u\n", @@ -1260,7 +1274,7 @@ static int xsk_append_merge_buffer(struct virtnet_inf= o *vi, =20 u64_stats_add(&stats->bytes, len); =20 - xdp =3D buf_to_xdp(vi, rq, buf, len); + xdp =3D buf_to_xdp(vi, rq, buf, len, false); if (!xdp) goto err; =20 @@ -1358,7 +1372,7 @@ static void virtnet_receive_xsk_buf(struct virtnet_in= fo *vi, struct receive_queu =20 u64_stats_add(&stats->bytes, len); =20 - xdp =3D buf_to_xdp(vi, rq, buf, len); + xdp =3D buf_to_xdp(vi, rq, buf, len, true); if (!xdp) return; =20 --=20 2.43.0