Bug 2536683 (CVE-2026-93095)

Summary:	CVE-2026-93095 kernel: hfsplus: validate thread record before delete key rebuild
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the HFS Plus (HFS+) filesystem in the Linux kernel. A local attacker could provide a specially crafted, corrupted HFS+ image that, when processed during a delete key rebuild operation, would cause the system to write past an allocated memory buffer. This out-of-bounds write could lead to memory corruption, potentially resulting in a denial of service or other unspecified impacts.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 19:05:15 UTC

In the Linux kernel, the following vulnerability has been resolved:

hfsplus: validate thread record before delete key rebuild

hfsplus_delete_cat() is called with str == NULL when the last open
reference to an unlinked HFS+ hardlink backing inode is closed. In that
case, the function finds the catalog thread by CNID and rebuilds the
catalog key from thread.nodeName.

That reconstruction path reads thread.nodeName.length directly from the
catalog B-tree into fd.search_key and then copies length * 2 bytes into
fd.search_key->cat.name.unicode. It does not first check that the found
record is a thread record or that its size matches the thread name.

A corrupted image can therefore provide an oversized thread name length
and make hfs_bnode_read() write past the catalog search-key allocation.

Read the CNID record through hfsplus_brec_read_cat(), which bounds the
record read to sizeof(hfsplus_cat_entry) and verifies that a thread
record's size exactly matches nodeName.length. Together, these checks
ensure an accepted thread name fits HFSPLUS_MAX_STRLEN. Reject non-thread
records before building the delete key from the validated thread name.

Share the thread-record-type helper between hfsplus_find_cat() and
hfsplus_delete_cat().

Comment 1 gkamathe 2026-09-19 05:11:26 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93095.mbox