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.

Fixes: bf3022a4eb11 ("mailbox: Add RISC-V SBI message proxy (MPXY) based mailbox driver")
Assisted-by: Codex:gpt-5
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>

0 files changed, 0 insertions, 0 deletions