[PATCH net-next v2 3/7] um: vector: trim skbs before verifying the header
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From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2026-10-15 12:41:43
Also in:
linux-um, lkml, virtualization
Subsystem:
the rest, user-mode linux (uml) · Maintainers:
Linus Torvalds, Richard Weinberger, Anton Ivanov, Johannes Berg
The vector receive path over-allocates the skb and only trims it to the received length after the transport header is verified. A follow up patch will complete the packet checksum in software within virtio_net_hdr_to_skb so we need the packet trimmed (otherwise the checksum would be computed incorrectly over the unreceived tail of the buffer). Trim first, so the import sees the packet as it was received. Assisted-by: LLM Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- arch/um/drivers/vector_kern.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index 8a70b3a62553..1afbef78df72 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c@@ -865,6 +865,7 @@ static int vector_legacy_rx(struct vector_private *vp) if (skb != NULL) { if (pkt_len > vp->header_size) { + pskb_trim(skb, pkt_len - vp->rx_header_size); if (vp->header_size > 0) { header_check = vp->verify_header( vp->header_rxbuffer, skb, vp);
@@ -879,7 +880,6 @@ static int vector_legacy_rx(struct vector_private *vp) skb->ip_summed = CHECKSUM_UNNECESSARY; } } - pskb_trim(skb, pkt_len - vp->rx_header_size); skb->protocol = eth_type_trans(skb, skb->dev); vp->dev->stats.rx_bytes += skb->len; vp->dev->stats.rx_packets++;
@@ -981,6 +981,8 @@ static int vector_mmsg_rx(struct vector_private *vp, int budget) for (i = 0; i < packet_count; i++) { skb = (*skbuff_vector); if (mmsg_vector->msg_len > vp->header_size) { + pskb_trim(skb, + mmsg_vector->msg_len - vp->rx_header_size); if (vp->header_size > 0) { header_check = vp->verify_header( mmsg_vector->msg_hdr.msg_iov->iov_base,
@@ -1005,8 +1007,6 @@ static int vector_mmsg_rx(struct vector_private *vp, int budget) skb->ip_summed = CHECKSUM_UNNECESSARY; } } - pskb_trim(skb, - mmsg_vector->msg_len - vp->rx_header_size); skb->protocol = eth_type_trans(skb, skb->dev); /* * We do not need to lock on updating stats here
--
MST