Bug 2516375 (CVE-2026-72202)

Summary: CVE-2026-72202 kernel: ntfs: avoid heap allocation for free-cluster readahead state
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's NTFS filesystem driver. When calculating free clusters or Master File Table (MFT) records, a temporary state object is allocated on the heap. If this allocation fails, processes waiting for these counts can become unresponsive, leading to a denial of service (DoS) for the system.
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Description OSIDB Bzimport 2026-08-15 06:09:13 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ntfs: avoid heap allocation for free-cluster readahead state

get_nr_free_clusters() allocates a temporary file_ra_state before it
publishes the precomputed free cluster count, sets NVolFreeClusterKnown(),
and wakes vol->free_waitq. If that allocation fails, the worker returns
without setting the flag or waking waiters, so callers waiting for the free
count can block indefinitely.

The readahead state is only used synchronously while scanning the bitmap.
Keep it on the stack and pass it by address to the readahead helper. This
eliminates the early allocation failure path instead of adding a special
case that publishes a conservative count and wakes the waitqueue.
Zero-initialize the on-stack state because file_ra_state_init() only sets
ra_pages and prev_pos.

Apply the same treatment to __get_nr_free_mft_records(), which scans the
MFT bitmap with the same short-lived readahead state.
Comment 1 Keith Grant 2026-08-18 15:12:28 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081543-CVE-2026-72202-5135@gregkh/T