AUGUST 4, 2026
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Case File

CVE-2021-47140

MEDIUM · CVSS 5.3 EPSS 0.60%

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2024-03-25 · Last synced 2026-08-04

CyberRota Analysis

This is a medium severity vulnerability with a CVSS score of 5.3. It affects Linux.

CVE
CVE-2021-47140
Severity
MEDIUM
CVSS
5.3
EPSS
0.60%
Linux

Original NVD Description

In the Linux kernel, the following vulnerability has been resolved: iommu/amd: Clear DMA ops when switching domain Since commit 08a27c1c3ecf ("iommu: Add support to change default domain of an iommu group") a user can switch a device between IOMMU and direct DMA through sysfs. This doesn't work for AMD IOMMU at the moment because dev->dma_ops is not cleared when switching from a DMA to an identity IOMMU domain. The DMA layer thus attempts to use the dma-iommu ops on an identity domain, causing an oops: # echo 0000:00:05.0 > /sys/sys/bus/pci/drivers/e1000e/unbind # echo identity > /sys/bus/pci/devices/0000:00:05.0/iommu_group/type # echo 0000:00:05.0 > /sys/sys/bus/pci/drivers/e1000e/bind ... BUG: kernel NULL pointer dereference, address: 0000000000000028 ... Call Trace: iommu_dma_alloc e1000e_setup_tx_resources e1000e_open Since iommu_change_dev_def_domain() calls probe_finalize() again, clear the dma_ops there like Vt-d does.

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