[PATCH net-next v6 6/7] tap: Keep hdr_len in tap_get_user()
From: Akihiko Odaki <hidden>
Date: 2025-02-07 06:11:47
Also in:
kvm, linux-doc, linux-kselftest, lkml, virtualization
Subsystem:
networking drivers, the rest, tun/tap driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Willem de Bruijn, Jason Wang
hdr_len is repeatedly used so keep it in a local variable. Signed-off-by: Akihiko Odaki <redacted> --- 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,
--
2.48.1