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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-80615
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-28 08:16:45 UTC
Updated2026-08-28 08:16:45 UTC
DescriptionIn 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 69050f8d6d075dc01af7a5f2f550a8067510366f 7ce31739fe88a558370135db95bbeec1e7ddfc29 git Not specified
CNA Linux Linux affected 69050f8d6d075dc01af7a5f2f550a8067510366f 4c6d43db2a4d2cef3921e885cf34798f790d34ea git Not specified
CNA Linux Linux affected 7.0 Not specified
CNA Linux Linux unaffected 7.0 semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/4c6d43db2a4d2cef3921e885cf34798f790d34ea 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7ce31739fe88a558370135db95bbeec1e7ddfc29 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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