CVE-2026-93096

Summary

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

cxl/features: Serialize multi-part Get/Set Feature transfers

A Get or Set Feature payload larger than the mailbox payload size is split into several mailbox commands. mbox_mutex only serializes individual mailbox commands and is dropped between iterations of these loops. Nothing serializes the multi-part transfer as a whole. cxl_get_feature() and cxl_set_feature() are reachable concurrently from fwctl (per-fd RPCs run under a read-held registration lock) and from the EDAC scrub/ECS/repair paths, so two transfers to the same mailbox can interleave their parts and corrupt the device's transfer context.

Add a per-mailbox feat_mutex and hold it across the whole transfer in both functions. It nests outside mbox_mutex (which is taken inside cxl_internal_send_cmd()), and is taken nowhere else, so no lock-ordering inversion is introduced.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/7682b617db1f19bc606b5f1badadcf1e63a87b14
• https://git.kernel.org/stable/c/77b814c1832fde018c30357b4ec3fcdaa91a1c10

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