Bug 2492436 (CVE-2026-52971)

Summary: CVE-2026-52971 kernel: net: ena: PHC: Fix potential use-after-free in get_timestamp
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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 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).
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Description OSIDB Bzimport 2026-06-24 18:11:58 UTC 
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.
Comment 1 Keith Grant 2026-06-25 21:03:15 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062439-CVE-2026-52971-0bf1@gregkh/T
Comment 7 Jon Orris 2026-09-17 05:45:08 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:68507 https://access.redhat.com/errata/RHSA-2026:68507
Comment 8 Jon Orris 2026-09-17 12:15:50 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:68570 https://access.redhat.com/errata/RHSA-2026:68570