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 <[email protected]>
Reported-by: H.J. Lu <[email protected]>
Fixes: 297d716f6260 ("power_supply: Change ownership from driver to core")
Cc: <[email protected]>
---
Changes since v2:
1. Add missing 'const'.
Changes since v1:
1. Re-work idea, use local variable instead of devm-like functions
(pointed out by Dmitry Torokhov).
2. Adjusted subject and commit message.
---
drivers/hid/hid-input.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 14aebe483219..53aeaf6252c7 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 */
--
1.9.1
On Mon, Aug 03, 2015 at 02:57:30PM +0900, Krzysztof Kozlowski wrote:
> 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 <[email protected]>
> Reported-by: H.J. Lu <[email protected]>
> Fixes: 297d716f6260 ("power_supply: Change ownership from driver to core")
> Cc: <[email protected]>
>
FWIW:
Reviewed-by: Dmitry Torokhov <[email protected]>
> ---
> Changes since v2:
> 1. Add missing 'const'.
>
> Changes since v1:
> 1. Re-work idea, use local variable instead of devm-like functions
> (pointed out by Dmitry Torokhov).
> 2. Adjusted subject and commit message.
> ---
> drivers/hid/hid-input.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index 14aebe483219..53aeaf6252c7 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 */
> --
> 1.9.1
>
--
Dmitry
On Mon, 3 Aug 2015, Krzysztof Kozlowski wrote:
> 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 <[email protected]>
> Reported-by: H.J. Lu <[email protected]>
> Fixes: 297d716f6260 ("power_supply: Change ownership from driver to core")
> Cc: <[email protected]>
Applied to for-4.2/upstream-fixes-devm-fixed, and thanks again Dmitry for
catching my mistake.
--
Jiri Kosina
SUSE Labs