[PATCH v4 9/9] firmware: arm_scmi: Validate PCC shared memory signature
From: Sudeep Holla <sudeep.holla@kernel.org>
Date: 2026-09-04 15:59:49
Also in:
arm-scmi
Subsystem:
system control & power/management interface (scpi/scmi) message protocol drivers, the rest · Maintainers:
Sudeep Holla, Linus Torvalds
Validate the PCC shared memory signature when setting up an SCMI PCC channel. Reject channels whose shared memory signature does not encode PCC_SIGNATURE combined with the PCC subspace ID, so misconfigured firmware is caught before the transport starts using the shared memory region. Reviewed-by: Jonathan Cameron <redacted> Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org> --- drivers/firmware/arm_scmi/transports/pcc.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/firmware/arm_scmi/transports/pcc.c b/drivers/firmware/arm_scmi/transports/pcc.c
index b7501f980d0b..86d4a097d8ec 100644
--- a/drivers/firmware/arm_scmi/transports/pcc.c
+++ b/drivers/firmware/arm_scmi/transports/pcc.c@@ -698,8 +698,11 @@ static void rx_callback(struct mbox_client *cl, void *m) } static int pcc_chan_validate_shmem(struct scmi_chan_info *cinfo, - struct scmi_pcc *smbox) + struct scmi_pcc *smbox, int ss_id) { + struct pcc_shared_mem __iomem *shmem = smbox->pchan->shmem; + u32 valid_signature = ss_id + PCC_SIGNATURE; + if (smbox->pchan->shmem_size < SCMI_PCC_SHMEM_OVERHEAD || smbox->pchan->shmem_size - SCMI_PCC_SHMEM_OVERHEAD < cinfo->max_msg_size) {
@@ -707,6 +710,11 @@ static int pcc_chan_validate_shmem(struct scmi_chan_info *cinfo, return -ENOSPC; } + if (ioread32(&shmem->header.signature) != valid_signature) { + dev_err(cinfo->dev, "invalid PCC shared memory signature\n"); + return -EINVAL; + } + return 0; }
@@ -742,7 +750,7 @@ static int pcc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, return ret; } - ret = pcc_chan_validate_shmem(cinfo, smbox); + ret = pcc_chan_validate_shmem(cinfo, smbox, ss_id); if (ret) { pcc_mbox_free_channel(smbox->pchan); return ret;
--
2.43.0