// For flags

CVE-2021-47140

iommu/amd: Clear DMA ops when switching domain

Severity Score

"-"
*CVSS v-

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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.

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: iommu/amd: borra las operaciones de DMA al cambiar de dominio. Desde el commit 08a27c1c3ecf ("iommu: agrega soporte para cambiar el dominio predeterminado de un grupo iommu"), un usuario puede cambiar un dispositivo entre IOMMU y DMA directo a través de sysfs. Esto no funciona para AMD IOMMU en este momento porque dev->dma_ops no se borra al cambiar de un DMA a un dominio IOMMU de identidad. Por lo tanto, la capa DMA intenta utilizar las operaciones dma-iommu en un dominio de identidad, lo que provoca un error: # 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 ... ERROR: desreferencia del puntero NULL del kernel, dirección: 0000000000000028 ... Seguimiento de llamadas: iommu_dma_alloc e1000e_setup_tx_resources e1000e_open Dado que iommu_change_dev_def_domain() llama a probe_finalize() nuevamente, borre dma_ops allí como lo hace Vt-d.

*Credits: N/A
CVSS Scores
Attack Vector
-
Attack Complexity
-
Privileges Required
-
User Interaction
-
Scope
-
Confidentiality
-
Integrity
-
Availability
-
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-03-04 CVE Reserved
  • 2024-03-25 CVE Published
  • 2024-03-26 EPSS Updated
  • 2024-08-04 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.11 < 5.12.9
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.11 < 5.12.9"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.11 < 5.13
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.11 < 5.13"
en
Affected