CVE-2026-72046

In the Linux kernel, the following vulnerability has been resolved:

gve: fix header buffer corruption with header-split and HW-GRO

The DQO RX datapath programs a per-buffer-queue-descriptor

header_buf_addr at post time and reads the split header back at

completion time. Both the post and the read currently index the

header buffer by queue position rather than by the buffer's identity:

- post (gve_rx_post_buffers_dqo): header_buf_addr is computed from

bufq->tail

- read (gve_rx_dqo): the header is read from desc_idx (the completion

queue head index)

This relies on the buffer-queue index and the completion-queue index

being equal for the start of every packet, i.e. on the device consuming

posted buffers and returning completions in the exact same order. That

assumption does not hold once HW-GRO is enabled with multiple

flows: coalesced segments are accepted and completed in an order that

may differ from the order buffers were posted, and segments from

different flows may interleave.

That results in two problems:

1. Wrong header slot on read. Because the read offset is derived from

the completion index (desc_idx) while the device wrote the header to

the address programmed for the buffer's buf_id, the driver can copy

a header belonging to a different packet. This shows up as

throughput drop (about 30% drop and large numbers of TCP

retransmissions) with header-split and HW-GRO both enabled and many

streams.

2. Header buffer reused while still owned by the device. The driver

advances bufq->head by one per completion and re-posts buffers based

on that. Arrival of N RX completions only guarantees that at least N

RX buffer descriptors have been read by the device. It does not

guarantee that the device has relinquished the ownership of all the

buffers corresponding to those N descriptors. With out-of-order

completions (e.g. the completion for a packet copied into buffer N

arrives before the completion for a packet copied into buffer N-1),

the driver can re-post and overwrite a header buffer that the device

is still going to write into, corrupting the header of a packet

whose completion has not yet been processed.

Fix both issues by indexing the header buffer by buf_id on both the post

and read paths. Reading from buf_id's slot is therefore always correct

regardless of completion ordering (fixes problem 1).

Indexing by buf_id also ties each header slot to the lifetime of its

buffer state. A buffer state is only returned to the free/recycle lists

when its own completion (buf_id) is processed, so its header slot can

only be re-posted after the device is done with it. This makes header

slot reuse safe under out-of-order completions (fixes problem 2).

Allocate (gve_rx_alloc_hdr_bufs) and free (gve_rx_free_hdr_bufs) the

header buffers based on num_buf_states to match the buf_id indexing.