CVE-2022-48868 dmaengine: idxd: Let probe fail when workqueue cannot be enabled

What is CVE-2022-48868?

CVE-2022-48868 is a medium-severity vulnerability in Linux kernel, published on 21 Aug 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:

dmaengine: idxd: Let probe fail when workqueue cannot be enabled

The workqueue is enabled when the appropriate driver is loaded and disabled when the driver is removed. When the driver is removed it assumes that the workqueue was enabled successfully and proceeds to free allocations made during workqueue enabling.

Failure during workqueue enabling does not prevent the driver from being loaded. This is because the error path within drv_enable_wq() returns success unless a second failure is encountered during the error path. By returning success it is possible to load the driver even if the workqueue cannot be enabled and allocations that do not exist are attempted to be freed during driver remove.

Some examples of problematic flows: (a)

idxd_dmaengine_drv_probe() -> drv_enable_wq() -> idxd_wq_request_irq(): In above flow, if idxd_wq_request_irq() fails then idxd_wq_unmap_portal() is called on error exit path, but drv_enable_wq() returns 0 because idxd_wq_disable() succeeds. The driver is thus loaded successfully.

idxd_dmaengine_drv_remove()->drv_disable_wq()->idxd_wq_unmap_portal() Above flow on driver unload triggers the WARN in devm_iounmap() because the device resource has already been removed during error path of drv_enable_wq().

(b)

idxd_dmaengine_drv_probe() -> drv_enable_wq() -> idxd_wq_request_irq(): In above flow, if idxd_wq_request_irq() fails then idxd_wq_init_percpu_ref() is never called to initialize the percpu counter, yet the driver loads successfully because drv_enable_wq() returns 0.

idxd_dmaengine_drv_remove()->__idxd_wq_quiesce()->percpu_ref_kill(): Above flow on driver unload triggers a BUG when attempting to drop the initial ref of the uninitialized percpu ref: BUG: kernel NULL pointer dereference, address: 0000000000000010

Fix the drv_enable_wq() error path by returning the original error that indicates failure of workqueue enabling. This ensures that the probe fails when an error is encountered and the driver remove paths are only attempted when the workqueue was enabled successfully.

Weakness: CWE-476

Which versions are affected by CVE-2022-48868?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2022-48868?

Apply the vendor's patch.

Is CVE-2022-48868 being exploited?

There is no known exploitation of CVE-2022-48868 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 DEBIAN-CVE-2022-48868, GHSA-35cf-498m-vj28, UBUNTU-CVE-2022-48868.