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Mon, 24 Aug 2026 13:24:53 -0700 (PDT) X-Received: by 2002:a05:6a20:ce4f:b0:3cb:d156:d362 with SMTP id adf61e73a8af0-3cd90fbd2admr2743167637.3.1787603093506; Mon, 24 Aug 2026 13:24:53 -0700 (PDT) Received: from localhost ([50.35.46.84]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-327f91d381csm31902753eec.19.2026.08.24.13.24.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Aug 2026 13:24:53 -0700 (PDT) Date: Mon, 24 Aug 2026 13:24:50 -0700 From: Jonathan Cameron To: Sudeep Holla Cc: arm-scmi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@meta.com, Cristian Marussi , Breno Leitao Subject: Re: [PATCH v3 9/9] firmware: arm_scmi: Validate PCC shared memory signature Message-ID: <20260824132450.000045ca@oss.qualcomm.com> In-Reply-To: <20260813-acpi_scmi_pcc-v3-9-cb6b88b4ebb3@kernel.org> References: <20260813-acpi_scmi_pcc-v3-0-cb6b88b4ebb3@kernel.org> <20260813-acpi_scmi_pcc-v3-9-cb6b88b4ebb3@kernel.org> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.51; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: arm-scmi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: bfH45LZdMRN7i9pI1WgX0UA89jnVBg5b X-Authority-Analysis: v=2.4 cv=OLAXGyaB c=1 sm=1 tr=0 ts=6a8ca896 cx=c_pps a=vVfyC5vLCtgYJKYeQD43oA==:117 a=qC1CW/w66vtJz1P9yTJxNA==:17 a=kj9zAlcOel0A:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=yx91gb_oNiZeI1HMLzn7:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=Xy_CICi7n2P0mFM9eQgA:9 a=CjuIK1q_8ugA:10 a=rl5im9kqc5Lf4LNbBjHf:22 X-Proofpoint-GUID: bfH45LZdMRN7i9pI1WgX0UA89jnVBg5b X-Proofpoint-Spam-Info: AW1haW4tMjYwODI0MDE3MiBTYWx0ZWRfX6y7NjgjWKxdZ Fe303pMDTeRNPsOIuGM6zDDgrZR/ms22ifKiii6v6oQXCoJUIRmHwYb7Xkte8gHrPvSKsQXzQ5X YeyCSAtYJjN1d+wDcPfhMgRzA8wlZIw= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI0MDE3MiBTYWx0ZWRfX4/dd3azWv4kS UqbyCvOP/QUWFo5wmWsX5xkYWFEhuZ973p5dgAsl6fuGsTTyDG5P75CHeO33b3etPh8t54TJGph SnU9eNrYONJ8KQHuVpksBo86trlFsN2Lkj4dRV4Hn3B0ERC8B4OH66xG4e0UjYaxf6nJlcaIPrQ I/FDje4KKyFM/jDZGy7JZ2XKVjI0z0Ds1aWB/bqE0jPS2Qog3cn8iKar7Fr9osOC6u5mznz1Zw3 efuj5YBc+xNZcyd3S9JHRw/kljAdm71nUy2459/Tdo6OhHIgQBuzEDm61VGV5BCOOD/ovigb6ER lbVdUA95eSEFQHfw9h5gBCPC7yHp1lm3LouP0cWRUKt8cEdeTEm76Z/3JAiY3XxhbaEDCGpJ1xg tCsMgoCOfOnEGEqjbqiA16tJF7k6lwbMDsVfnsHgMC3ANhGHnP9wWo3NpoxZLj8rJwYcRSphMZM lL34DxHLphs/7vLe8+Q== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-24_06,2026-08-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 adultscore=0 malwarescore=0 suspectscore=0 priorityscore=1501 spamscore=0 phishscore=0 lowpriorityscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608240172 On Thu, 13 Aug 2026 12:33:04 +0100 Sudeep Holla wrote: > 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. > > Signed-off-by: Sudeep Holla Interesting there aren't more checks on this in the various PCC users. Question for another day perhaps. Seems correct to me. Reviewed-by: Jonathan Cameron > --- > 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 337d551e3ad8..0ead0ec77162 100644 > --- a/drivers/firmware/arm_scmi/transports/pcc.c > +++ b/drivers/firmware/arm_scmi/transports/pcc.c > @@ -623,8 +623,11 @@ 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) { > @@ -632,6 +635,11 @@ 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; > } > > @@ -667,7 +675,7 @@ 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; >