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.

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Source ID Title
Ubuntu USN Ubuntu USN USN-8887-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8888-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8889-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8887-2 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8888-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8887-3 Linux kernel vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 01 Sep 2026 12:15:00 +0000


Sat, 29 Aug 2026 08:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-787

Sat, 29 Aug 2026 06:45:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H'}


Fri, 28 Aug 2026 07:30:00 +0000

Type Values Removed Values Added
Description 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.
Title net: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-29T06:21:24.054Z

Reserved: 2026-08-26T14:34:25.774Z

Link: CVE-2026-80615

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-28T08:16:45.523

Modified: 2026-08-29T07:16:46.377

Link: CVE-2026-80615

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-08-28T00:00:00Z

Links: CVE-2026-80615 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-29T08:15:06Z

Weaknesses