Time-of-check Time-of-use (TOCTOU) Affecting kernel-zfcpdump-devel-matched package, versions *


Severity

Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.01% (2nd percentile)

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  • Snyk IDSNYK-CENTOS10-KERNELZFCPDUMPDEVELMATCHED-16943405
  • published28 May 2026
  • disclosed27 May 2026

Introduced: 27 May 2026

NewCVE-2026-45944  (opens in a new tab)
CWE-367  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-zfcpdump-devel-matched.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-zfcpdump-devel-matched package and not the kernel-zfcpdump-devel-matched package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

iommu/vt-d: Clear Present bit before tearing down context entry

When tearing down a context entry, the current implementation zeros the entire 128-bit entry using multiple 64-bit writes. This creates a window where the hardware can fetch a "torn" entry — where some fields are already zeroed while the 'Present' bit is still set — leading to unpredictable behavior or spurious faults.

While x86 provides strong write ordering, the compiler may reorder writes to the two 64-bit halves of the context entry. Even without compiler reordering, the hardware fetch is not guaranteed to be atomic with respect to multiple CPU writes.

Align with the "Guidance to Software for Invalidations" in the VT-d spec (Section 6.5.3.3) by implementing the recommended ownership handshake:

  1. Clear only the 'Present' (P) bit of the context entry first to signal the transition of ownership from hardware to software.
  2. Use dma_wmb() to ensure the cleared bit is visible to the IOMMU.
  3. Perform the required cache and context-cache invalidation to ensure hardware no longer has cached references to the entry.
  4. Fully zero out the entry only after the invalidation is complete.

Also, add a dma_wmb() to context_set_present() to ensure the entry is fully initialized before the 'Present' bit becomes visible.

CVSS Base Scores

version 3.1