gve: Fix stats report corruption on queue count change

commit 7b9ebcce0296e104a0d82a6b09d68564806158ff upstream.

The driver and the NIC share a region in memory for stats reporting.
The NIC calculates its offset into this region based on the total size
of the stats region and the size of the NIC's stats.

When the number of queues is changed, the driver's stats region is
resized. If the queue count is increased, the NIC can write past
the end of the allocated stats region, causing memory corruption.
If the queue count is decreased, there is a gap between the driver
and NIC stats, leading to incorrect stats reporting.

This change fixes the issue by allocating stats region with maximum
size, and the offset calculation for NIC stats is changed to match
with the calculation of the NIC.

BUG=b/494188002
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2026-23262 in the Linux kernel.

cos-patch: security-moderate
Cc: stable@vger.kernel.org
Fixes: 24aeb56f2d38 ("gve: Add Gvnic stats AQ command and ethtool show/set-priv-flags.")
Change-Id: I5d5dbe98bb1910a8f1586aee76f4fc34c45ed698
Signed-off-by: Debarghya Kundu <debarghyak@google.com>
Reviewed-by: Joshua Washington <joshwash@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260202193925.3106272-2-hramamurthy@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kernel CVE Triage Automation <cloud-image-kernel-cve-triage-automation@prod.google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/138901
Reviewed-by: Dom Huh <domhuh@google.com>
Reviewed-by: Miri Amarilio <mirilio@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>