CVE-2024-56568 iommu/arm-smmu: Defer probe of clients after smmu device bound

What is CVE-2024-56568?

CVE-2024-56568 is a medium-severity vulnerability in Linux kernel, published on 27 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

iommu/arm-smmu: Defer probe of clients after smmu device bound

Null pointer dereference occurs due to a race between smmu driver probe and client driver probe, when of_dma_configure() for client is called after the iommu_device_register() for smmu driver probe has executed but before the driver_bound() for smmu driver has been called.

Following is how the race occurs:

T1:Smmu device probe T2: Client device probe

really_probe() arm_smmu_device_probe() iommu_device_register() really_probe() platform_dma_configure() of_dma_configure() of_dma_configure_id() of_iommu_configure() iommu_probe_device() iommu_init_device() arm_smmu_probe_device() arm_smmu_get_by_fwnode() driver_find_device_by_fwnode() driver_find_device() next_device() klist_next() /* null ptr assigned to smmu */ /* null ptr dereference while smmu->streamid_mask */ driver_bound() klist_add_tail()

When this null smmu pointer is dereferenced later in arm_smmu_probe_device, the device crashes.

Fix this by deferring the probe of the client device until the smmu device has bound to the arm smmu driver.

[will: Add comment]

Weakness: CWE-362, CWE-476

Which versions are affected by CVE-2024-56568?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-56568?

Apply the vendor's patch.

Is CVE-2024-56568 being exploited?

There is no known exploitation of CVE-2024-56568 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-56274, AZL-56312, BELL-CVE-2024-56568, DEBIAN-CVE-2024-56568, GHSA-mfcg-4w9q-f9mr, UBUNTU-CVE-2024-56568.