ext4: allow ext4_get_group_info() to fail

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2023-53503
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-10-01 12:15:53 UTC
Updated2026-04-06 14:45:08 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ext4: allow ext4_get_group_info() to fail Previously, ext4_get_group_info() would treat an invalid group number as BUG(), since in theory it should never happen. However, if a malicious attaker (or fuzzer) modifies the superblock via the block device while it is the file system is mounted, it is possible for s_first_data_block to get set to a very large number. In that case, when calculating the block group of some block number (such as the starting block of a preallocation region), could result in an underflow and very large block group number. Then the BUG_ON check in ext4_get_group_info() would fire, resutling in a denial of service attack that can be triggered by root or someone with write access to the block device. For a quality of implementation perspective, it's best that even if the system administrator does something that they shouldn't, that it will not trigger a BUG. So instead of BUG'ing, ext4_get_group_info() will call ext4_error and return NULL. We also add fallback code in all of the callers of ext4_get_group_info() that it might NULL. Also, since ext4_get_group_info() was already borderline to be an inline function, un-inline it. The results in a next reduction of the compiled text size of ext4 by roughly 2k.

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: CWE-476

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 2f2e09eb15849562aede80ed007658e4504ded26 100c0ad6c04597fefeaaba2bb1827cc015d95067 git Not specified
CNA Linux Linux affected 2f2e09eb15849562aede80ed007658e4504ded26 620a3c28221bb219b81bc0bffd065cc187494302 git Not specified
CNA Linux Linux affected 2f2e09eb15849562aede80ed007658e4504ded26 b4319e457d6e3fb33e443efeaf4634fc36e8a9ed git Not specified
CNA Linux Linux affected 2f2e09eb15849562aede80ed007658e4504ded26 31668cebf45adfb6283e465e641c4f5a21b07afa git Not specified
CNA Linux Linux affected 2f2e09eb15849562aede80ed007658e4504ded26 5354b2af34064a4579be8bc0e2f15a7b70f14b5f git Not specified
CNA Linux Linux affected 3.11 Not specified
CNA Linux Linux unaffected 3.11 semver Not specified
CNA Linux Linux unaffected 5.10.181 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.113 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.30 6.1.* semver Not specified
CNA Linux Linux unaffected 6.3.4 6.3.* semver Not specified
CNA Linux Linux unaffected 6.4 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/620a3c28221bb219b81bc0bffd065cc187494302 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/b4319e457d6e3fb33e443efeaf4634fc36e8a9ed 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/5354b2af34064a4579be8bc0e2f15a7b70f14b5f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/31668cebf45adfb6283e465e641c4f5a21b07afa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/100c0ad6c04597fefeaaba2bb1827cc015d95067 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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