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

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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 from the RX FIFO
so they do not leak into the next transfer.

Fixes: dd3c52846d ("i3c: master: svc: Add Silvaco I3C master driver")
Cc: stable@vger.kernel.org
Co-developed-by: Kaixuan Li <kaixuan.li@ntu.edu.sg>
Signed-off-by: Kaixuan Li <kaixuan.li@ntu.edu.sg>
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/178227747353.2931373.15868718612134648277@maoyixie.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

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Maoyi Xie 2026-06-24 13:04:33 +08:00 • committed by Alexandre Belloni

parent f479d3033e

commit e2bda39d7f

1 changed files with 9 additions and 1 deletions

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drivers/i3c/master/svc-i3c-master.c

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