cxl/mbox: Clamp mailbox output allocation to the payload size

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-93186
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:18:14 UTC
Updated2026-09-17 17:18:14 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: cxl/mbox: Clamp mailbox output allocation to the payload size CXL_MEM_SEND_COMMAND bounds the user's in.size to the mailbox payload size but leaves out.size unbounded, then cxl_mbox_cmd_ctor() calls kvzalloc(out.size). A large out.size drives a huge allocation, above INT_MAX it WARNs and taints, and with panic_on_warn=1 it panics. The transport __cxl_pci_mbox_send_cmd() already clamps the response copy to min(out.size, payload_size, device len), so the output buffer is never written beyond payload_size. Clamp the allocation to payload_size too, matching the RAW path.

Risk And Classification

EPSS: 0.001860000 probability, percentile 0.084890000 (date 2026-09-19)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 583fa5e71caeb79e04e477e9837e2f7fa53b71e4 f5d2bbf0300f46307948864fbb97bce5097f4fe2 git Not specified
CNA Linux Linux affected 583fa5e71caeb79e04e477e9837e2f7fa53b71e4 31d4841eca7c4b75751ca96d24339e19303337f2 git Not specified
CNA Linux Linux affected 583fa5e71caeb79e04e477e9837e2f7fa53b71e4 b4e11c731d6bee3b87315e055a1ca417c92dc1fc git Not specified
CNA Linux Linux affected 583fa5e71caeb79e04e477e9837e2f7fa53b71e4 8a13db9f899d149c3aab24abcb668121cfda5a4f git Not specified
CNA Linux Linux affected 5.12 Not specified
CNA Linux Linux unaffected 5.12 semver Not specified
CNA Linux Linux unaffected 6.12.110 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.52 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/31d4841eca7c4b75751ca96d24339e19303337f2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b4e11c731d6bee3b87315e055a1ca417c92dc1fc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8a13db9f899d149c3aab24abcb668121cfda5a4f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f5d2bbf0300f46307948864fbb97bce5097f4fe2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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