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 3511bba..e3c6364 100644 (file)
--- 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 */