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From:   Sibi Sankar <quic_sibis@quicinc.com>
To:     <sudeep.holla@arm.com>, <cristian.marussi@arm.com>
CC:     <linux-arm-msm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <quic_mdtipton@quicinc.com>,
        <linux-arm-kernel@lists.infradead.org>, <quic_asartor@quicinc.com>,
        <quic_lingutla@quicinc.com>, Sibi Sankar <quic_sibis@quicinc.com>
Subject: [PATCH 1/3] firmware: arm_scmi: Fix null pointer dereference during fastchannel init
Date:   Wed, 29 Nov 2023 12:27:46 +0530
Message-ID: <20231129065748.19871-2-quic_sibis@quicinc.com>
In-Reply-To: <20231129065748.19871-1-quic_sibis@quicinc.com>
References: <20231129065748.19871-1-quic_sibis@quicinc.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

The scmi_perf_domain_lookup requires the protocol handle to have the
private data set, which is yet to happen during the fastchannel init
scenario. This results in a null pointer dereference. Fix this by using
the pre-populated perf_dom_info to pass on the required information
instead.

Call trace:
scmi_perf_protocol_init+0x434/0x678
scmi_get_protocol_instance+0x168/0x29c
scmi_devres_protocol_instance_get+0x50/0xa0
scmi_devm_protocol_get+0x20/0x50
scmi_cpufreq_probe+0x34/0xd4
scmi_dev_probe+0x28/0x3c
really_probe+0x148/0x2ac
__driver_probe_device+0x78/0x12c
driver_probe_device+0x40/0x160
__device_attach_driver+0xb8/0x134
bus_for_each_drv+0x80/0xdc
__device_attach+0xa8/0x1b0
device_initial_probe+0x14/0x20
bus_probe_device+0xa8/0xac
device_add+0x5cc/0x778
device_register+0x20/0x30
__scmi_device_create.part.0+0xec/0x1cc
scmi_device_create+0x180/0x1c4
scmi_create_protocol_devices+0x4c/0xb0
scmi_probe+0x660/0x738
platform_probe+0x68/0xdc
really_probe+0x148/0x2ac
__driver_probe_device+0x78/0x12c
driver_probe_device+0x40/0x160
__device_attach_driver+0xb8/0x134
bus_for_each_drv+0x80/0xdc
__device_attach+0xa8/0x1b0
device_initial_probe+0x14/0x20
bus_probe_device+0xa8/0xac
deferred_probe_work_func+0x88/0xc0
process_one_work+0x13c/0x264
worker_thread+0x32c/0x438
kthread+0x118/0x11c
ret_from_fork+0x10/0x20

Fixes: 619bc6e034f3 ("firmware: arm_scmi: Populate fastchannel info only if set operations are allowed")
Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
---
 drivers/firmware/arm_scmi/perf.c | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
index d1323c5d9c27..a648521e04a3 100644
--- a/drivers/firmware/arm_scmi/perf.c
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -759,40 +759,35 @@ static int scmi_perf_level_limits_notify(const struct scmi_protocol_handle *ph,
 }
 
 static void scmi_perf_domain_init_fc(const struct scmi_protocol_handle *ph,
-				     u32 domain, struct scmi_fc_info **p_fc)
+				     struct perf_dom_info *dom)
 {
 	struct scmi_fc_info *fc;
-	struct perf_dom_info *dom;
-
-	dom = scmi_perf_domain_lookup(ph, domain);
-	if (IS_ERR(dom))
-		return;
 
 	fc = devm_kcalloc(ph->dev, PERF_FC_MAX, sizeof(*fc), GFP_KERNEL);
 	if (!fc)
 		return;
 
 	ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-				   PERF_LEVEL_GET, 4, domain,
+				   PERF_LEVEL_GET, 4, dom->id,
 				   &fc[PERF_FC_LEVEL].get_addr, NULL);
 
 	ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-				   PERF_LIMITS_GET, 8, domain,
+				   PERF_LIMITS_GET, 8, dom->id,
 				   &fc[PERF_FC_LIMIT].get_addr, NULL);
 
 	if (dom->info.set_perf)
 		ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-					   PERF_LEVEL_SET, 4, domain,
+					   PERF_LEVEL_SET, 4, dom->id,
 					   &fc[PERF_FC_LEVEL].set_addr,
 					   &fc[PERF_FC_LEVEL].set_db);
 
 	if (dom->set_limits)
 		ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
-					   PERF_LIMITS_SET, 8, domain,
+					   PERF_LIMITS_SET, 8, dom->id,
 					   &fc[PERF_FC_LIMIT].set_addr,
 					   &fc[PERF_FC_LIMIT].set_db);
 
-	*p_fc = fc;
+	dom->fc_info = fc;
 }
 
 static int scmi_dvfs_device_opps_add(const struct scmi_protocol_handle *ph,
@@ -1102,7 +1097,7 @@ static int scmi_perf_protocol_init(const struct scmi_protocol_handle *ph)
 		scmi_perf_describe_levels_get(ph, dom, version);
 
 		if (dom->perf_fastchannels)
-			scmi_perf_domain_init_fc(ph, dom->id, &dom->fc_info);
+			scmi_perf_domain_init_fc(ph, dom);
 	}
 
 	ret = devm_add_action_or_reset(ph->dev, scmi_perf_xa_destroy, pinfo);
-- 
2.17.1