net: stmmac: fix TX descriptor availability check for TSO traffic

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-97953
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-25 11:17:22 UTC
Updated2026-09-25 15:18:02 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix TX descriptor availability check for TSO traffic stmmac_tso_xmit() estimates the number of free TX descriptors required by a TSO skb as: (skb->len - proto_hdr_len) / TSO_MAX_BUFF_SIZE + 1 which assumes the payload is split into TSO_MAX_BUFF_SIZE chunks. This underestimates the descriptors actually consumed by stmmac_tso_allocator(), since each fragment is mapped individually and so it needs at least one descriptor regardless of its size. Moreover, one descriptor is used for the L2/L3/L4 headers and, when the MSS changes, one more is consumed for the MSS context descriptor. For a highly fragmented TSO skb the check can therefore pass even when the ring has too few free slots. stmmac_tso_allocator() then writes past the available descriptors, overwriting descriptors still owned by the DMA engine, corrupting the TX ring. Add stmmac_tso_get_num_desc() to compute the exact number of descriptors needed for the header, the linear payload and each fragment, plus the MSS context descriptor when required, and use it in the availability check.

Risk And Classification

Primary CVSS: v3.1 7 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.004100000 probability, percentile 0.326590000 (date 2026-09-27)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
3.1CNADECLARED7HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected f748be531d7012c456b97f66091d86b3675c5fef ffa6d2481bc1c87f822ecd626561484e4ee24cef git Not specified
CNA Linux Linux affected f748be531d7012c456b97f66091d86b3675c5fef c28175220f808c867d5618de8ecc6dbcc815c773 git Not specified
CNA Linux Linux affected f748be531d7012c456b97f66091d86b3675c5fef 65820fc743eae322f7f94f6a64d07861211d4b21 git Not specified
CNA Linux Linux affected f748be531d7012c456b97f66091d86b3675c5fef 5e38d732ec67a5b1f9a56e6c73add480c4b6030a git Not specified
CNA Linux Linux affected 4.7 Not specified
CNA Linux Linux unaffected 4.7 semver Not specified
CNA Linux Linux unaffected 6.12.111 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.53 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.7 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/c28175220f808c867d5618de8ecc6dbcc815c773 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ffa6d2481bc1c87f822ecd626561484e4ee24cef 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5e38d732ec67a5b1f9a56e6c73add480c4b6030a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/65820fc743eae322f7f94f6a64d07861211d4b21 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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