ufs: validate cylinder group metadata before caching it

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-97926
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-25 11:17:19 UTC
Updated2026-09-25 15:18:02 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ufs: validate cylinder group metadata before caching it ufs_read_cylinder() copies the cylinder group index and the rotor positions straight from the on-disk group and caches them without any check: ucpi->c_cgx = fs32_to_cpu(sb, ucg->cg_cgx); ucpi->c_rotor = fs32_to_cpu(sb, ucg->cg_rotor); ucpi->c_frotor = fs32_to_cpu(sb, ucg->cg_frotor); ucpi->c_irotor = fs32_to_cpu(sb, ucg->cg_irotor); They are then used as indices during allocation and free: - c_cgx indexes the cylinder summary array as UFS_SB(sb)->fs_cs(ucpi->c_cgx), so a value past s_ncg writes a 32 bit count outside the s_csp allocation. - c_frotor becomes a bitmap scan start, start = c_frotor >> 3, and then length = ((s_fpg + 7) >> 3) - start. A start beyond the block bitmap wraps the unsigned length to a huge value, so ubh_scanc() walks far past the cylinder group buffers. c_irotor drives the inode bitmap the same way. A crafted image can set any of these freely, turning an ordinary allocation into an out of bounds access. Reject a cylinder group whose recorded index does not match the group being read, or whose rotors fall outside the group, before the metadata is cached. Valid filesystems keep cg_cgx equal to the group number and the rotors within the group, so only malformed images are rejected.

Risk And Classification

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

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

EPSS: 0.001540000 probability, percentile 0.038040000 (date 2026-09-27)

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

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 5902a95066883cf96fa15b2680694fc5dd0c7d11 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 87b12dc360a002eb2d498aa4f01e84347019612d git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 abde9eb33106850dfa367ad3965d3588bb8558d5 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 c9d263be26806d388129fab8c6904bed197fc6af git Not specified
CNA Linux Linux affected 2.6.12 Not specified
CNA Linux Linux unaffected 2.6.12 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/87b12dc360a002eb2d498aa4f01e84347019612d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/abde9eb33106850dfa367ad3965d3588bb8558d5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5902a95066883cf96fa15b2680694fc5dd0c7d11 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c9d263be26806d388129fab8c6904bed197fc6af 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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