From 04e6ccfc93c5a1aa1d75a537cf27e418895e20ea Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Thu, 14 Dec 2023 11:52:25 +0100
Subject: [PATCH] thermal: core: Fix NULL pointer dereference in zone registration error path
Git-commit: 04e6ccfc93c5a1aa1d75a537cf27e418895e20ea
Patch-mainline: v6.8-rc1
References: git-fixes CVE-2023-52473 bsc#1220430

If device_register() in thermal_zone_device_register_with_trips()
returns an error, the tz variable is set to NULL and subsequently
dereferenced in kfree(tz->tzp).

Commit adc8749b150c ("thermal/drivers/core: Use put_device() if
device_register() fails") added the tz = NULL assignment in question to
avoid a possible double-free after dropping the reference to the zone
device.  However, after commit 4649620d9404 ("thermal: core: Make
thermal_zone_device_unregister() return after freeing the zone"), that
assignment has become redundant, because dropping the reference to the
zone device does not cause the zone object to be freed any more.

Drop it to address the NULL pointer dereference.

Fixes: 3d439b1a2ad3 ("thermal/core: Alloc-copy-free the thermal zone parameters structure")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/thermal/thermal_core.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 2415dc50c31d..5e5fcbd81dda 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -1393,7 +1393,6 @@ thermal_zone_device_register_with_trips(const char *type, struct thermal_trip *t
 	device_del(&tz->device);
 release_device:
 	put_device(&tz->device);
-	tz = NULL;
 remove_id:
 	ida_free(&thermal_tz_ida, id);
 free_tzp:
-- 
2.35.3