CVE-2026-90191

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

mailbox: riscv-sbi-mpxy: validate RPMI notification lengths

The SBI return value controls how many bytes are copied from shared
memory into the RPMI notification buffer. It is not validated against
the negotiated shared-memory size before that copy. The event walker
also uses a reversed loop condition and can inspect a short event record.

Validate the complete notification length before copying it, iterate only
while a full event header remains, and stop when a declared event payload
extends beyond the copied notification data.