linux-kernel - [PATCH] drivers core: lookup sysfs power group before removal

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Message-Id: <20231101173627.2658-1-jose.pekkarinen@foxhound.fi>
Date:   Wed,  1 Nov 2023 19:36:27 +0200
From:   José Pekkarinen <jose.pekkarinen@...hound.fi>
To:     rafael@...nel.org, len.brown@...el.com, pavel@....cz,
        gregkh@...uxfoundation.org, skhan@...uxfoundation.org
Cc:     José Pekkarinen <jose.pekkarinen@...hound.fi>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        syzbot+95f2e2439b97575ec3c0@...kaller.appspotmail.com
Subject: [PATCH] drivers core: lookup sysfs power group before removal

Hinted by syzboot, there is a few cases where the sysfs power group may
not be there, like the failure while adding it, or adding its runtime
group, or when the sysfs firmware loader fallback fail to populate. In
the last case, the device_del function will be called leading to attempt
to remove the sysfs group. This patch will lookup for it in advance to
grant that it is effectively there before cleaning it up.

Reported-by: syzbot+95f2e2439b97575ec3c0@...kaller.appspotmail.com

Signed-off-by: José Pekkarinen <jose.pekkarinen@...hound.fi>
---
 drivers/base/power/sysfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index a1474fb67db9..6601729c4698 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -834,5 +834,7 @@ void dpm_sysfs_remove(struct device *dev)
 	dev_pm_qos_constraints_destroy(dev);
 	rpm_sysfs_remove(dev);
 	sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
-	sysfs_remove_group(&dev->kobj, &pm_attr_group);
+
+	if (kernfs_find_and_get((&dev->kobj)->sd, pm_attr_group.name))
+		sysfs_remove_group(&dev->kobj, &pm_attr_group);
 }
-- 
2.39.2