CVE-2025-37868

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

drm/xe/userptr: fix notifier vs folio deadlock

User is reporting what smells like notifier vs folio deadlock, where migrate_pages_batch() on core kernel side is holding folio lock(s) and then interacting with the mappings of it, however those mappings are tied to some userptr, which means calling into the notifier callback and grabbing the notifier lock. With perfect timing it looks possible that the pages we pulled from the hmm fault can get sniped by migrate_pages_batch() at the same time that we are holding the notifier lock to mark the pages as accessed/dirty, but at this point we also want to grab the folio locks(s) to mark them as dirty, but if they are contended from notifier/migrate_pages_batch side then we deadlock since folio lock wont be dropped until we drop the notifier lock.

Fortunately the mark_page_accessed/dirty is not really needed in the first place it seems and should have already been done by hmm fault, so just remove it.

(cherry picked from commit bd7c0cb695e87c0e43247be8196b4919edbe0e85)

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• https://git.kernel.org/stable/c/2577b202458cddff85cc154b1fe7f313e0d1f418
• https://git.kernel.org/stable/c/65dc4e3d5b01db0179fc95c1f0bdb87194c28ab5
• https://git.kernel.org/stable/c/90574ecf6052be83971d91d16600c5cf07003bbb