2023-01-09 23:08:06

by Bjorn Andersson

[permalink] [raw]
Subject: [PATCH] rpmsg: glink: Release driver_override

Upon termination of the rpmsg_device, driver_override needs to be freed
to avoid leaking the potentially assigned string.

Fixes: 42cd402b8fd4 ("rpmsg: Fix kfree() of static memory on setting driver_override")
Fixes: 39e47767ec9b ("rpmsg: Add driver_override device attribute for rpmsg_device")
Signed-off-by: Bjorn Andersson <[email protected]>
---
drivers/rpmsg/qcom_glink_native.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index 8620eea1dc8a..046271e439c5 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -1454,6 +1454,7 @@ static void qcom_glink_rpdev_release(struct device *dev)
{
struct rpmsg_device *rpdev = to_rpmsg_device(dev);

+ kfree(rpdev->driver_override);
kfree(rpdev);
}

@@ -1697,6 +1698,7 @@ static void qcom_glink_device_release(struct device *dev)

/* Release qcom_glink_alloc_channel() reference */
kref_put(&channel->refcount, qcom_glink_channel_release);
+ kfree(rpdev->driver_override);
kfree(rpdev);
}

--
2.37.3


2023-01-18 01:11:32

by Chris Lew

[permalink] [raw]
Subject: Re: [PATCH] rpmsg: glink: Release driver_override



On 1/9/2023 2:38 PM, Bjorn Andersson wrote:
> Upon termination of the rpmsg_device, driver_override needs to be freed
> to avoid leaking the potentially assigned string.
>
> Fixes: 42cd402b8fd4 ("rpmsg: Fix kfree() of static memory on setting driver_override")
> Fixes: 39e47767ec9b ("rpmsg: Add driver_override device attribute for rpmsg_device")
> Signed-off-by: Bjorn Andersson <[email protected]>
> ---
> drivers/rpmsg/qcom_glink_native.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index 8620eea1dc8a..046271e439c5 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -1454,6 +1454,7 @@ static void qcom_glink_rpdev_release(struct device *dev)
> {
> struct rpmsg_device *rpdev = to_rpmsg_device(dev);
>
> + kfree(rpdev->driver_override);

I see in Krzysztof's original patch to fix up the driver_override we do
kfree in other areas of rpmsg.

More of a just curious as to why don't we use the driver_set_override
function to clear the string? It's mentioned in the rpmsg header that
the helper should be used.

--- include/linux/rpmsg.h
* @driver_override: driver name to force a match; do not set directly,
* because core frees it; use driver_set_override() to
* set or clear it.

> kfree(rpdev);
> }
>
> @@ -1697,6 +1698,7 @@ static void qcom_glink_device_release(struct device *dev)
>
> /* Release qcom_glink_alloc_channel() reference */
> kref_put(&channel->refcount, qcom_glink_channel_release);
> + kfree(rpdev->driver_override);
> kfree(rpdev);
> }
>
>

2023-01-18 18:02:54

by Bjorn Andersson

[permalink] [raw]
Subject: Re: [PATCH] rpmsg: glink: Release driver_override

On Tue, Jan 17, 2023 at 05:01:01PM -0800, Chris Lew wrote:
>
>
> On 1/9/2023 2:38 PM, Bjorn Andersson wrote:
> > Upon termination of the rpmsg_device, driver_override needs to be freed
> > to avoid leaking the potentially assigned string.
> >
> > Fixes: 42cd402b8fd4 ("rpmsg: Fix kfree() of static memory on setting driver_override")
> > Fixes: 39e47767ec9b ("rpmsg: Add driver_override device attribute for rpmsg_device")
> > Signed-off-by: Bjorn Andersson <[email protected]>
> > ---
> > drivers/rpmsg/qcom_glink_native.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> > index 8620eea1dc8a..046271e439c5 100644
> > --- a/drivers/rpmsg/qcom_glink_native.c
> > +++ b/drivers/rpmsg/qcom_glink_native.c
> > @@ -1454,6 +1454,7 @@ static void qcom_glink_rpdev_release(struct device *dev)
> > {
> > struct rpmsg_device *rpdev = to_rpmsg_device(dev);
> > + kfree(rpdev->driver_override);
>
> I see in Krzysztof's original patch to fix up the driver_override we do
> kfree in other areas of rpmsg.
>

Right, in the original patch what became driver_set_override() was open
coded and hence there was a kfree().

> More of a just curious as to why don't we use the driver_set_override
> function to clear the string? It's mentioned in the rpmsg header that the
> helper should be used.
>
> --- include/linux/rpmsg.h
> * @driver_override: driver name to force a match; do not set directly,
> * because core frees it; use driver_set_override() to
> * set or clear it.
>

Looking around the kernel, just calling kfree() in the release function
seems to be how others are doing it as well. As such I presume that
comment applies to the runtime state, rather than while we're cleaning
things up.

Regards,
Bjorn

> > kfree(rpdev);
> > }
> > @@ -1697,6 +1698,7 @@ static void qcom_glink_device_release(struct device *dev)
> > /* Release qcom_glink_alloc_channel() reference */
> > kref_put(&channel->refcount, qcom_glink_channel_release);
> > + kfree(rpdev->driver_override);
> > kfree(rpdev);
> > }
> >

2023-01-25 06:27:19

by Chris Lew

[permalink] [raw]
Subject: Re: [PATCH] rpmsg: glink: Release driver_override



On 1/18/2023 9:50 AM, Bjorn Andersson wrote:
> On Tue, Jan 17, 2023 at 05:01:01PM -0800, Chris Lew wrote:
>>
>>
>> On 1/9/2023 2:38 PM, Bjorn Andersson wrote:
>>> Upon termination of the rpmsg_device, driver_override needs to be freed
>>> to avoid leaking the potentially assigned string.
>>>
>>> Fixes: 42cd402b8fd4 ("rpmsg: Fix kfree() of static memory on setting driver_override")
>>> Fixes: 39e47767ec9b ("rpmsg: Add driver_override device attribute for rpmsg_device")
>>> Signed-off-by: Bjorn Andersson <[email protected]>
>>> ---
>>> drivers/rpmsg/qcom_glink_native.c | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
>>> index 8620eea1dc8a..046271e439c5 100644
>>> --- a/drivers/rpmsg/qcom_glink_native.c
>>> +++ b/drivers/rpmsg/qcom_glink_native.c
>>> @@ -1454,6 +1454,7 @@ static void qcom_glink_rpdev_release(struct device *dev)
>>> {
>>> struct rpmsg_device *rpdev = to_rpmsg_device(dev);
>>> + kfree(rpdev->driver_override);
>>
>> I see in Krzysztof's original patch to fix up the driver_override we do
>> kfree in other areas of rpmsg.
>>
>
> Right, in the original patch what became driver_set_override() was open
> coded and hence there was a kfree().
>
>> More of a just curious as to why don't we use the driver_set_override
>> function to clear the string? It's mentioned in the rpmsg header that the
>> helper should be used.
>>
>> --- include/linux/rpmsg.h
>> * @driver_override: driver name to force a match; do not set directly,
>> * because core frees it; use driver_set_override() to
>> * set or clear it.
>>
>
> Looking around the kernel, just calling kfree() in the release function
> seems to be how others are doing it as well. As such I presume that
> comment applies to the runtime state, rather than while we're cleaning
> things up.
>
> Regards,
> Bjorn
>

Got it - should be safe to follow how others are handling this in cleanup.

Reviewed-by: Chris Lew <[email protected]>

>>> kfree(rpdev);
>>> }
>>> @@ -1697,6 +1698,7 @@ static void qcom_glink_device_release(struct device *dev)
>>> /* Release qcom_glink_alloc_channel() reference */
>>> kref_put(&channel->refcount, qcom_glink_channel_release);
>>> + kfree(rpdev->driver_override);
>>> kfree(rpdev);
>>> }
>>>