CVE-2026-68400

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

firmware: arm_ffa: Fix Endpoint Memory Access Descriptor offset calculation

Use the descriptor's ep_mem_offset to calculate the start of the endpoint memory access array and to comply with the FF-A spec instead of defaulting to sizeof(struct ffa_mem_region). This requires moving ffa_mem_region_additional_setup() earlier in the setup flow. Also, add sanity checks to ensure the calculated descriptor offsets do not exceed max_fragsize.