Bug 2535074 (CVE-2026-89781)

Summary: CVE-2026-89781 kernel: fs/ntfs3: fix out-of-bounds read in read_log_rec_buf()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: 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 Linux kernel's NTFS3 file system driver. A local user could exploit this vulnerability by mounting a specially crafted NTFS image. This could lead to an out-of-bounds read, allowing the disclosure of sensitive information from adjacent memory areas.
 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 2026-09-16 09:12:02 UTC 
In the Linux kernel, the following vulnerability has been resolved:

fs/ntfs3: fix out-of-bounds read in read_log_rec_buf()

read_log_rec_buf() copies a log record into a caller buffer starting at

	u32 off = lsn_to_page_off(log, lsn) + log->record_header_len;

log->record_header_len (and log->data_off, used for the following pages)
comes verbatim from the on-disk restart area and is only checked for
8-byte alignment in is_rst_area_valid(), so off can exceed
log->page_size. "tail = log->page_size - off" then underflows and
memcpy() reads past the page_size-sized buffer returned by
read_log_page(), spilling adjacent slab memory into the replay buffer.

This is reachable by mounting a crafted NTFS image:

 BUG: KASAN: slab-out-of-bounds in read_log_rec_buf+0x216/0x580
 Read of size 64 at addr ffff88800a877ff8 by task exploit/127
  read_log_rec_buf fs/ntfs3/fslog.c:2299
  log_replay fs/ntfs3/fslog.c:4216
  ntfs_loadlog_and_replay fs/ntfs3/fsntfs.c:324
  ntfs_fill_super fs/ntfs3/super.c:1392
  get_tree_bdev_flags fs/super.c:1694
  __x64_sys_mount fs/namespace.c:4360
 The buggy address is located 4088 bytes to the right of
 the 4096-byte region [ffff88800a876000, ffff88800a877000)

Reject an in-page offset outside the current page before the copy.

[almaz.alexandrovich: replaced the >= sign with >]
Comment 1 Keith Grant 2026-09-21 19:33:44 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89781.mbox