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Thu, 06 Feb 2025 22:11:46 -0800 (PST) Received: from localhost ([157.82.205.237]) by smtp.gmail.com with UTF8SMTPSA id d9443c01a7336-21f3650cd10sm22742625ad.31.2025.02.06.22.11.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Feb 2025 22:11:46 -0800 (PST) From: Akihiko Odaki Date: Fri, 07 Feb 2025 15:10:56 +0900 Subject: [PATCH net-next v6 6/7] tap: Keep hdr_len in tap_get_user() Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250207-tun-v6-6-fb49cf8b103e@daynix.com> References: <20250207-tun-v6-0-fb49cf8b103e@daynix.com> In-Reply-To: <20250207-tun-v6-0-fb49cf8b103e@daynix.com> To: Jonathan Corbet , Willem de Bruijn , Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , "Michael S. Tsirkin" , Xuan Zhuo , Shuah Khan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kselftest@vger.kernel.org, Yuri Benditovich , Andrew Melnychenko , Stephen Hemminger , gur.stavi@huawei.com, devel@daynix.com, Akihiko Odaki X-Mailer: b4 0.14.2 hdr_len is repeatedly used so keep it in a local variable. Signed-off-by: Akihiko Odaki Reviewed-by: Willem de Bruijn --- drivers/net/tap.c | 28 ++++++++++------------------ 1 file changed, 10 insertions(+), 18 deletions(-) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index 5aa41d5f7765a6dcf185bccd3cba2299bad89398..8cb002616a6143b54258b65b483fed0c3af2c7a0 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -645,6 +645,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, int err; struct virtio_net_hdr vnet_hdr = { 0 }; int vnet_hdr_len = 0; + int hdr_len = 0; int copylen = 0; int depth; bool zerocopy = false; @@ -663,13 +664,13 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from)) goto err; iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr)); - if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && - tap16_to_cpu(q, vnet_hdr.csum_start) + - tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 > - tap16_to_cpu(q, vnet_hdr.hdr_len)) - vnet_hdr.hdr_len = cpu_to_tap16(q, - tap16_to_cpu(q, vnet_hdr.csum_start) + - tap16_to_cpu(q, vnet_hdr.csum_offset) + 2); + hdr_len = tap16_to_cpu(q, vnet_hdr.hdr_len); + if (vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) { + hdr_len = max(tap16_to_cpu(q, vnet_hdr.csum_start) + + tap16_to_cpu(q, vnet_hdr.csum_offset) + 2, + hdr_len); + vnet_hdr.hdr_len = cpu_to_tap16(q, hdr_len); + } err = -EINVAL; if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len) goto err; @@ -682,12 +683,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { struct iov_iter i; - copylen = vnet_hdr.hdr_len ? - tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; - if (copylen > good_linear) - copylen = good_linear; - else if (copylen < ETH_HLEN) - copylen = ETH_HLEN; + copylen = clamp(hdr_len ?: GOODCOPY_LEN, ETH_HLEN, good_linear); linear = copylen; i = *from; iov_iter_advance(&i, copylen); @@ -697,11 +693,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, if (!zerocopy) { copylen = len; - linear = tap16_to_cpu(q, vnet_hdr.hdr_len); - if (linear > good_linear) - linear = good_linear; - else if (linear < ETH_HLEN) - linear = ETH_HLEN; + linear = clamp(hdr_len, ETH_HLEN, good_linear); } skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,