CVE-2026-80951

/// Technical description

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

i3c: master: svc: bound IBI payload to the requested max_payload_len

svc_i3c_master_handle_ibi() reads the IBI payload from the RX FIFO into

the IBI slot. The loop is bounded by the hardware FIFO size

(SVC_I3C_FIFO_SIZE), not by the slot size.

slot->data points into the IBI pool, which i3c_generic_ibi_alloc_pool()

sizes at max_payload_len per slot. svc_i3c_master_request_ibi() only

rejects a max_payload_len larger than SVC_I3C_FIFO_SIZE, so a driver can

request a smaller one. mctp-i3c requests 1. Each readsb() then copies the

controller RXCOUNT bytes (up to 31) with no check against the slot size.

A device that sends more bytes than the slot holds writes past

slot->data, an out-of-bounds write into the IBI pool.

Bound the loop by dev->ibi->max_payload_len and clamp each read to the

space left in the slot, the same way dw-i3c does. A device can still send

more than the requested payload. Flush the leftover bytes fro

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References