mm/slab: do not limit zeroing to orig_size when only red zoning is enabled

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-64368
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-25 10:17:19 UTC
Updated2026-07-27 05:16:43 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm/slab: do not limit zeroing to orig_size when only red zoning is enabled When init (zeroing) on allocation is requested, for kmalloc() we generally have to zero the full object size even if a smaller size is requested, in order to provide krealloc()'s __GFP_ZERO guarantees. But if we track the requested size, krealloc() uses that information to do the right thing, so we can zero only the requested size. With red zoning also enabled, any extra size became part of the red zone, so it must not be zeroed and thus we must zero only the requested size. However the current check is imprecise, and will trigger also when only SLAB_RED_ZONE is enabled without SLAB_STORE_USER (which enables tracking the requested size). This means enabling red zoning alone can compromise krealloc()'s __GFP_ZERO contract. Fix this by using slub_debug_orig_size() instead, which is the exact check for whether the requested size is tracked. We don't need to care if red zoning is also enabled or not. Also update and expand the comment accordingly.

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.004170000 probability, percentile 0.341600000 (date 2026-07-27)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.1HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.1HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 9ce67395f5a0cdec6ce152d26bfda13b98b25c01 6256899c3a34674bba6076884aedbba49fc695e4 git Not specified
CNA Linux Linux affected 9ce67395f5a0cdec6ce152d26bfda13b98b25c01 7e706d50fa119eead6376bf0ef973e8d73a96030 git Not specified
CNA Linux Linux affected 9ce67395f5a0cdec6ce152d26bfda13b98b25c01 2382971aaaef5bf85a651234c64906f59580b8be git Not specified
CNA Linux Linux affected 9ce67395f5a0cdec6ce152d26bfda13b98b25c01 0d18ccef142f04433dfb2a0c120cf223d2b8a42c git Not specified
CNA Linux Linux affected 9ce67395f5a0cdec6ce152d26bfda13b98b25c01 648927ceb84021a25a0fbd5673740956f318d534 git Not specified
CNA Linux Linux affected 6.2 Not specified
CNA Linux Linux unaffected 6.2 semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.96 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.39 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.4 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/2382971aaaef5bf85a651234c64906f59580b8be 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7e706d50fa119eead6376bf0ef973e8d73a96030 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/648927ceb84021a25a0fbd5673740956f318d534 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6256899c3a34674bba6076884aedbba49fc695e4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0d18ccef142f04433dfb2a0c120cf223d2b8a42c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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