CVE-2026-99242
ntfs: fix race between fallocate and mmap reads
What happened?
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.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| LinuxLinux | affected: 495e90fa334828d4119061e2726af51d0a0fb4ed to < 7dd1c2fec6ebdd1a88a02cb58ff515a258eeb327; affected: 495e90fa334828d4119061e2726af51d0a0fb4ed to < 67aded1da114dc44808315f249bd9e7e440f799d | See vendor advisory |
| LinuxLinux | affected: 7.1; unaffected: 0 to < 7.1; unaffected: 7.2.14 to ≤ 7.2.*; unaffected: 7.3 to ≤ * | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.