CVE-2021-47140 iommu/amd: Clear DMA ops when switching domain
A local attacker with sysfs access can trigger a kernel null pointer dereference and crash the system by switching IOMMU domains on AMD hardware.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-47140?
CVE-2021-47140 is a medium-severity vulnerability in Linux kernel, published on 25 Mar 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-476
Which versions are affected by CVE-2021-47140?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47140?
Apply the vendor's patch.
Is CVE-2021-47140 being exploited?
There is no known exploitation of CVE-2021-47140 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47140, GHSA-vr5f-v75p-g4qw, UBUNTU-CVE-2021-47140.