From: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Date: Mon, 3 Aug 2015 05:57:30 +0000 (+0900)
Subject: HID: hid-input: Fix accessing freed memory during device disconnect
X-Git-Tag: firefly_0821_release~176^2~1174^2~5
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=0621809e37936e7c2b3eac9165cf2aad7f9189eb;p=firefly-linux-kernel-4.4.55.git

HID: hid-input: Fix accessing freed memory during device disconnect

During unbinding the driver was dereferencing a pointer to memory
already freed by power_supply_unregister().

Driver was freeing its internal description of battery through pointers
stored in power_supply structure. However, because the core owns the
power supply instance, after calling power_supply_unregister() this
memory is freed and the driver cannot access these members.

Fix this by storing the pointer to internal description of battery in a
local variable before calling power_supply_unregister(), so the pointer
remains valid.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reported-by: H.J. Lu <hjl.tools@gmail.com>
Fixes: 297d716f6260 ("power_supply: Change ownership from driver to core")
Cc: <stable@vger.kernel.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
---

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 3511bbaba505..e3c63640df73 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -462,12 +462,15 @@ out:
 
 static void hidinput_cleanup_battery(struct hid_device *dev)
 {
+	const struct power_supply_desc *psy_desc;
+
 	if (!dev->battery)
 		return;
 
+	psy_desc = dev->battery->desc;
 	power_supply_unregister(dev->battery);
-	kfree(dev->battery->desc->name);
-	kfree(dev->battery->desc);
+	kfree(psy_desc->name);
+	kfree(psy_desc);
 	dev->battery = NULL;
 }
 #else  /* !CONFIG_HID_BATTERY_STRENGTH */