CVE-2025-38584

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

padata: Fix pd UAF once and for all

There is a race condition/UAF in padata_reorder that goes back to the initial commit. A reference count is taken at the start of the process in padata_do_parallel, and released at the end in padata_serial_worker.

This reference count is (and only is) required for padata_replace to function correctly. If padata_replace is never called then there is no issue.

In the function padata_reorder which serves as the core of padata, as soon as padata is added to queue->serial.list, and the associated spin lock released, that padata may be processed and the reference count on pd would go away.

Fix this by getting the next padata before the squeue->serial lock is released.

In order to make this possible, simplify padata_reorder by only calling it once the next padata arrives.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/71203f68c7749609d7fc8ae6ad054bdedeb24f91
• https://git.kernel.org/stable/c/cdf79bd2e1ecb3cc75631c73d8f4149be6019a52
• https://git.kernel.org/stable/c/dbe3e911a59bda6de96e7cae387ff882c2c177fa