[PATCH 4.1 21/78] HID: hid-input: Fix accessing freed memory during device disconnect

Greg Kroah-Hartman
2015-09-11T23:05:48Z

From: Krzysztof Kozlowski <k.kozlowski@samsung.com>

commit 0621809e37936e7c2b3eac9165cf2aad7f9189eb upstream.

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")
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hid/hid-input.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- 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 */