vmxnet3: Fix malformed packet sizing in vmxnet3_process_xdp

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-37799
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-05-03 12:15:14 UTC
Updated2026-07-30 06:22:20 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: vmxnet3: Fix malformed packet sizing in vmxnet3_process_xdp vmxnet3 driver's XDP handling is buggy for packet sizes using ring0 (that is, packet sizes between 128 - 3k bytes). We noticed MTU-related connectivity issues with Cilium's service load- balancing in case of vmxnet3 as NIC underneath. A simple curl to a HTTP backend service where the XDP LB was doing IPIP encap led to overly large packet sizes but only for *some* of the packets (e.g. HTTP GET request) while others (e.g. the prior TCP 3WHS) looked completely fine on the wire. In fact, the pcap recording on the backend node actually revealed that the node with the XDP LB was leaking uninitialized kernel data onto the wire for the affected packets, for example, while the packets should have been 152 bytes their actual size was 1482 bytes, so the remainder after 152 bytes was padded with whatever other data was in that page at the time (e.g. we saw user/payload data from prior processed packets). We only noticed this through an MTU issue, e.g. when the XDP LB node and the backend node both had the same MTU (e.g. 1500) then the curl request got dropped on the backend node's NIC given the packet was too large even though the IPIP-encapped packet normally would never even come close to the MTU limit. Lowering the MTU on the XDP LB (e.g. 1480) allowed to let the curl request succeed (which also indicates that the kernel ignored the padding, and thus the issue wasn't very user-visible). Commit e127ce7699c1 ("vmxnet3: Fix missing reserved tailroom") was too eager to also switch xdp_prepare_buff() from rcd->len to rbi->len. It really needs to stick to rcd->len which is the actual packet length from the descriptor. The latter we also feed into vmxnet3_process_xdp_small(), by the way, and it indicates the correct length needed to initialize the xdp->{data,data_end} parts. For e127ce7699c1 ("vmxnet3: Fix missing reserved tailroom") the relevant part was adapting xdp_init_buff() to address the warning given the xdp_data_hard_end() depends on xdp->frame_sz. With that fixed, traffic on the wire looks good again.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: NVD-CWE-noinfo

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.6HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
3.1CNADECLARED8.6HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected aba8659caf88017507419feea06069f529329ea6 c4312c4d244aa58e811ff0297e013124d115e793 git Not specified
CNA Linux Linux affected e127ce7699c1e05279ee5ee61f00893e7bfa9671 33e131a10459d16f181c8184d3f17f1c318c7002 git Not specified
CNA Linux Linux affected e127ce7699c1e05279ee5ee61f00893e7bfa9671 e3ad76e36a37b0ff4a71b06d5b33530ee8c3a177 git Not specified
CNA Linux Linux affected e127ce7699c1e05279ee5ee61f00893e7bfa9671 4c2227656d9003f4d77afc76f34dd81b95e4c2c4 git Not specified
CNA Linux Linux affected 7c8505ecc2d15473d679b8e06335434b84fffe86 git Not specified
CNA Linux Linux affected 91d017d19d5a9ad153e2dc23ed3c0e2e79ef5262 git Not specified
CNA Linux Linux affected 6.6.23 6.6.89 semver Not specified
CNA Linux Linux affected 6.7.11 6.8 semver Not specified
CNA Linux Linux affected 6.8.2 6.9 semver Not specified
CNA Linux Linux affected 6.9 Not specified
CNA Linux Linux unaffected 6.9 semver Not specified
CNA Linux Linux unaffected 6.6.89 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.26 6.12.* semver Not specified
CNA Linux Linux unaffected 6.14.5 6.14.* semver Not specified
CNA Linux Linux unaffected 6.15 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/c4312c4d244aa58e811ff0297e013124d115e793 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/e3ad76e36a37b0ff4a71b06d5b33530ee8c3a177 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/33e131a10459d16f181c8184d3f17f1c318c7002 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/4c2227656d9003f4d77afc76f34dd81b95e4c2c4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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