Medium [CVE-2026-72202] avoid heap allocation for free-cluster readahead state
This medium-severity Red Hat Linux advisory covers CVE-2026-72202.
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Summary
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.
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. Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-833.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 24 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 24 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 24 days ago·verify at source
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