linux-kernel - [PATCH RFC] PM: EM: Add to em_pd

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20251028-fix-energy-v1-1-ab854fd6a97c@nxp.com>
Date: Tue, 28 Oct 2025 22:23:32 +0800
From: Peng Fan <peng.fan@....com>
To: Lukasz Luba <lukasz.luba@....com>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, Pavel Machek <pavel@...nel.org>, 
 Len Brown <lenb@...nel.org>, Changwoo Min <changwoo@...lia.com>, 
 Ulf Hansson <ulf.hansson@...aro.org>, Sudeep Holla <sudeep.holla@....com>, 
 Cristian Marussi <cristian.marussi@....com>
Cc: arm-scmi@...r.kernel.org, 
 "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, linux-pm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: [PATCH RFC] PM: EM: Add to em_pd_list only when no failure

When em_create_perf_table() returns failure, pd is freed, there dev->em_pd
is not valid. Then accessing dev->em_pd->node will trigger kernel panic
in em_dev_register_pd_no_update(). So return early if 'ret' is non-zero.

Kernel dump:
cpu cpu0: EM: invalid power: 0
Unable to handle kernel NULL pointer dereference at virtual address
0000000000000008
Mem abort info:
pc : em_dev_register_pd_no_update+0xb4/0x79c
lr : em_dev_register_pd_no_update+0x9c/0x79c
Call trace:
 em_dev_register_pd_no_update+0xb4/0x79c (P)
 em_dev_register_perf_domain+0x18/0x58
 scmi_cpufreq_register_em+0x84/0xb8
 cpufreq_online+0x48c/0xb74
 cpufreq_add_dev+0x80/0x98
 subsys_interface_register+0x100/0x11c
 cpufreq_register_driver+0x158/0x278
 scmi_cpufreq_probe+0x1f8/0x2e0
 scmi_dev_probe+0x28/0x3c
 really_probe+0xbc/0x29c
 __driver_probe_device+0x78/0x12c
 driver_probe_device+0x3c/0x15c
 __device_attach_driver+0xb8/0x134
 bus_for_each_drv+0x84/0xe4

Fixes: cbe5aeedecc7 ("PM: EM: Assign a unique ID when creating a performance domain")
Signed-off-by: Peng Fan <peng.fan@....com>
---
 kernel/power/energy_model.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index e669d5057fca6da9612575a1c626474e60e7f7c4..11af9f64aa8276e47e0a5b2d615b227368af5480 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -693,13 +693,16 @@ int em_dev_register_pd_no_update(struct device *dev, unsigned int nr_states,

 unlock:
 	mutex_unlock(&em_pd_mutex);
+	if (ret)
+		return ret;

 	mutex_lock(&em_pd_list_mutex);
 	list_add_tail(&dev->em_pd->node, &em_pd_list);
 	mutex_unlock(&em_pd_list_mutex);

 	em_notify_pd_created(dev->em_pd);
-	return ret;
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(em_dev_register_pd_no_update);

---
base-commit: f7d2388eeec24966fc4d5cf32d706f0514f29ac5
change-id: 20251028-fix-energy-6b63b72ae9c6

Best regards,
-- 
Peng Fan <peng.fan@....com>