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() the
driver cannot access these members.
Fix this by using resource-managed allocations so internal data will be
freed by pointers stored in resource-managed core.
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]>
---
drivers/hid/hid-input.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 14aebe483219..5429a8497d51 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -408,15 +408,14 @@ static bool hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
if (dev->battery != NULL)
goto out; /* already initialized? */
- psy_desc = kzalloc(sizeof(*psy_desc), GFP_KERNEL);
+ psy_desc = devm_kzalloc(&dev->dev, sizeof(*psy_desc), GFP_KERNEL);
if (psy_desc == NULL)
goto out;
- psy_desc->name = kasprintf(GFP_KERNEL, "hid-%s-battery", dev->uniq);
- if (psy_desc->name == NULL) {
- kfree(psy_desc);
+ psy_desc->name = devm_kasprintf(&dev->dev, GFP_KERNEL,
+ "hid-%s-battery", dev->uniq);
+ if (psy_desc->name == NULL)
goto out;
- }
psy_desc->type = POWER_SUPPLY_TYPE_BATTERY;
psy_desc->properties = hidinput_battery_props;
@@ -449,8 +448,6 @@ static bool hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
if (IS_ERR(dev->battery)) {
hid_warn(dev, "can't register power supply: %ld\n",
PTR_ERR(dev->battery));
- kfree(psy_desc->name);
- kfree(psy_desc);
dev->battery = NULL;
} else {
power_supply_powers(dev->battery, &dev->dev);
@@ -466,8 +463,6 @@ static void hidinput_cleanup_battery(struct hid_device *dev)
return;
power_supply_unregister(dev->battery);
- kfree(dev->battery->desc->name);
- kfree(dev->battery->desc);
dev->battery = NULL;
}
#else /* !CONFIG_HID_BATTERY_STRENGTH */
--
1.9.1
On Tue, 28 Jul 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() the
> driver cannot access these members.
>
> Fix this by using resource-managed allocations so internal data will be
> freed by pointers stored in resource-managed core.
>
> 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, thanks.
--
Jiri Kosina
SUSE Labs
On Wed, Jul 29, 2015 at 03:07:04PM +0200, Jiri Kosina wrote:
> On Tue, 28 Jul 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() the
> > driver cannot access these members.
> >
> > Fix this by using resource-managed allocations so internal data will be
> > freed by pointers stored in resource-managed core.
> >
> > 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, thanks.
Wait, what guarantees do we have that this is only called in probe()
paths? Don't we allow hid_hw_start() be deferred to open() calls?
In general we need to be careful with devm* conversions in core code.
Thanks.
--
Dmitry
2015-07-30 2:46 GMT+09:00 Dmitry Torokhov <[email protected]>:
> On Wed, Jul 29, 2015 at 03:07:04PM +0200, Jiri Kosina wrote:
>> On Tue, 28 Jul 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() the
>> > driver cannot access these members.
>> >
>> > Fix this by using resource-managed allocations so internal data will be
>> > freed by pointers stored in resource-managed core.
>> >
>> > 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, thanks.
>
> Wait, what guarantees do we have that this is only called in probe()
> paths? Don't we allow hid_hw_start() be deferred to open() calls?
Indeed, this may be called in other contexts. But this should not
introduce errors except not reclaimable memory (till remove()
happens).
> In general we need to be careful with devm* conversions in core code.
>
Another and less intrusive fix would be:
char *name = dev->battery->desc->name;
struct power_supply_desc *psy_desc = dev->battery->desc;
power_supply_unregister(dev->battery);
kfree(name);
kfree(psy_desc);
How about this?
Best regards,
Krzysztof
On Thu, Jul 30, 2015 at 08:42:12AM +0900, Krzysztof Kozlowski wrote:
> 2015-07-30 2:46 GMT+09:00 Dmitry Torokhov <[email protected]>:
> > On Wed, Jul 29, 2015 at 03:07:04PM +0200, Jiri Kosina wrote:
> >> On Tue, 28 Jul 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() the
> >> > driver cannot access these members.
> >> >
> >> > Fix this by using resource-managed allocations so internal data will be
> >> > freed by pointers stored in resource-managed core.
> >> >
> >> > 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, thanks.
> >
> > Wait, what guarantees do we have that this is only called in probe()
> > paths? Don't we allow hid_hw_start() be deferred to open() calls?
>
> Indeed, this may be called in other contexts. But this should not
> introduce errors except not reclaimable memory (till remove()
> happens).
>
> > In general we need to be careful with devm* conversions in core code.
> >
>
> Another and less intrusive fix would be:
>
> char *name = dev->battery->desc->name;
> struct power_supply_desc *psy_desc = dev->battery->desc;
> power_supply_unregister(dev->battery);
> kfree(name);
> kfree(psy_desc);
I would much rather prefer this to the other version as it does not
leave memory hanging around, potentially indefinitely, but ultimately it
is up to Jiri. I only hope that power supply code does not reference
power_supply_desc pointer past unregister (since the device structure
itself may live past the point where power_supply_unregister() returns).
By the way, you do not need name temp, you can do
kfree(psy_desc->name);
kfree(psy_desc);
Thanks.
--
Dmitry
On Wed, 29 Jul 2015, Dmitry Torokhov wrote:
> > Another and less intrusive fix would be:
> >
> > char *name = dev->battery->desc->name;
> > struct power_supply_desc *psy_desc = dev->battery->desc;
> > power_supply_unregister(dev->battery);
> > kfree(name);
> > kfree(psy_desc);
>
> I would much rather prefer this to the other version as it does not
> leave memory hanging around, potentially indefinitely, but ultimately it
> is up to Jiri.
I must have been in some broken state of mind when applying the original
one, thanks a lot for catching my brainfart, Dmitry!
Kryzstof, could you please send me properly formatted patch with the
above, on top of your previous fix?
Thanks.
--
Jiri Kosina
SUSE Labs
2015-08-01 21:11 GMT+09:00 Jiri Kosina <[email protected]>:
> On Wed, 29 Jul 2015, Dmitry Torokhov wrote:
>
>> > Another and less intrusive fix would be:
>> >
>> > char *name = dev->battery->desc->name;
>> > struct power_supply_desc *psy_desc = dev->battery->desc;
>> > power_supply_unregister(dev->battery);
>> > kfree(name);
>> > kfree(psy_desc);
>>
>> I would much rather prefer this to the other version as it does not
>> leave memory hanging around, potentially indefinitely, but ultimately it
>> is up to Jiri.
>
> I must have been in some broken state of mind when applying the original
> one, thanks a lot for catching my brainfart, Dmitry!
>
> Kryzstof, could you please send me properly formatted patch with the
> above, on top of your previous fix?
Of course, I'll send next version.
Best regards,
Krzysztof