Bug 2565273 (CVE-2026-99242) - CVE-2026-99242 kernel: kernel: Information disclosure via race condition between fallocate and mmap reads in NTFS
Summary: CVE-2026-99242 kernel: kernel: Information disclosure via race condition betw...
Keywords:
Status: NEW
Alias: CVE-2026-99242
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-11-02 16:45 UTC by OSIDB Bzimport
Modified: 2026-11-04 15:04 UTC (History)
17 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-11-02 16:45:39 UTC
In the Linux kernel, the following vulnerability has been resolved:

ntfs: fix race between fallocate and mmap reads

The fallocate implementation only takes invalidate_lock for punch hole,
collapse range, and insert range operations. For standard allocation modes
(mode == 0, FALLOC_FL_KEEP_SIZE), the lock is not held.

During ntfs_attr_fallocate(), new clusters are mapped to the runlist via
ntfs_attr_map_cluster() before being zeroed by ntfs_dio_zero_range(). This
creates a window where concurrent mmap page faults can read uninitialized
disk data.

Since mmap uses filemap_fault() which takes invalidate_lock in shared mode,
it can fault in pages during this window and expose old disk contents to
userspace. This is an information leak and data integrity issue.

Fix by taking invalidate_lock for all fallocate operations, not just for
punch/collapse/insert modes. This prevents concurrent page faults from
accessing unzeroed clusters during the allocation window.


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