High [CVE-2026-52971] Fix potential use-after-free in get_timestamp
This high-severity Red Hat Linux advisory covers CVE-2026-52971 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
In the Linux kernel, the following vulnerability has been resolved: net: ena: PHC: Fix potential use-after-free in get_timestamp Move the phc->active check and resp pointer assignment to after acquiring the spinlock. Previously, phc->active was checked without holding the lock, and resp was cached from ena_dev->phc.virt_addr before the lock was acquired.
If ena_com_phc_destroy() runs between the lockless active check and the lock acquisition, it sets active=false, releases the lock, frees the DMA memory, and sets virt_addr=NULL. The get_timestamp path would then read a NULL virt_addr and dereference it.
With both the active check and the pointer read under the lock, destroy cannot free the memory while get_timestamp is using it. A flaw was found in the Linux kernel's Elastic Network Adapter (ENA) driver, specifically within the Precision Time Protocol Hardware Clock (PHC) timestamp retrieval function.
A race condition exists where the `get_timestamp` function could attempt to access memory that has already been freed by the `ena_com_phc_destroy` function. This use-after-free vulnerability can lead to a NULL pointer dereference, potentially causing a system crash and resulting in a Denial of Service (DoS).
Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-825.
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 9 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 9 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 9 days ago·verify at source
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