---
id: CVE-2026-80615
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone

  kmalloc_flex() in metadata_dst_alloc() sets __counted_by for the
  structure to the options_len,…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone

  kmalloc_flex() in metadata_dst_alloc() sets __counted_by for the
  structure to the options_len,…
severity: high
cvss: 8.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H'
published: '2026-08-28'
updated: '2026-08-29'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-80615'
references:
  - url: 'https://git.kernel.org/stable/c/4c6d43db2a4d2cef3921e885cf34798f790d34ea'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7ce31739fe88a558370135db95bbeec1e7ddfc29'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00489
epssPercentile: 0.39504
ingestedAt: '2026-08-29T23:43:56.241Z'
---

## Overview

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

net: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone

kmalloc_flex() in metadata_dst_alloc() sets __counted_by for the
structure to the options_len, which is then initialized to zero.
Later, we're initializing the structure by copying the tunnel info
together with the options, and this triggers a warning for a potential
memcpy overflow, since the compiler estimates that the options can't
fit into the structure, even though the memory for them is actually
allocated.

 memcpy: detected buffer overflow: 104 byte write of buffer size 96
 WARNING: CPU: X PID: Y at lib/string_helpers.c:1036 __fortify_report
  skb_tunnel_info_unclone+0x179/0x190
  geneve_xmit+0x7fe/0xe00

The issue is triggered when built with clang and source fortification.

Fix that by doing the copy in two stages: first - the main data with
the options_len, then the options.  This way the correct length should
be known at the time of the copy.

It would be better if the options_len never changed after allocation,
but the allocation code is a little separate from the initialization
and it would be awkward and potentially dangerous to return a struct
with options_len set to a non-zero value from the metadata_dst_alloc().

Another option would be to use ip_tunnel_info_opts_set(), but it is
doing too many unnecessary operations for the use case here.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.