linux-kernel - Re: [PATCH] iio: accel: kxcjk-1013: Fix possible memory leak in probe and remove

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Date:   Thu, 14 Oct 2021 20:41:10 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Yang Yingliang <yangyingliang@...wei.com>,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        lars@...afoo.de, andriy.shevchenko@...ux.intel.com,
        ddvlad@...il.com
Subject: Re: [PATCH] iio: accel: kxcjk-1013: Fix possible memory leak in probe
 and remove

Hi,

On 10/14/21 7:38 PM, Jonathan Cameron wrote:
> On Thu, 14 Oct 2021 10:20:34 +0200
> Hans de Goede <hdegoede@...hat.com> wrote:
> 
>> Hi,
>>
>> On 10/14/21 5:53 AM, Yang Yingliang wrote:
>>> When ACPI type is ACPI_SMO8500, the data->dready_trig will not be set, the
>>> memory allocated by iio_triggered_buffer_setup() will not be freed, and cause
>>> memory leak as follows:
>>>
>>> unreferenced object 0xffff888009551400 (size 512):
>>>   comm "i2c-SMO8500-125", pid 911, jiffies 4294911787 (age 83.852s)
>>>   hex dump (first 32 bytes):
>>>     02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>>>     00 00 00 00 00 00 00 00 20 e2 e5 c0 ff ff ff ff  ........ .......
>>>   backtrace:
>>>     [<0000000041ce75ee>] kmem_cache_alloc_trace+0x16d/0x360
>>>     [<000000000aeb17b0>] iio_kfifo_allocate+0x41/0x130 [kfifo_buf]
>>>     [<000000004b40c1f5>] iio_triggered_buffer_setup_ext+0x2c/0x210 [industrialio_triggered_buffer]
>>>     [<000000004375b15f>] kxcjk1013_probe+0x10c3/0x1d81 [kxcjk_1013]
>>>     [<0000000020115b9a>] i2c_device_probe+0xa31/0xbe0
>>>     [<00000000d9f581a6>] really_probe+0x299/0xc30
>>>     [<00000000c6c16cde>] __driver_probe_device+0x357/0x500
>>>     [<00000000909852a1>] driver_probe_device+0x4e/0x140
>>>     [<000000008419ba53>] __device_attach_driver+0x257/0x340
>>>     [<00000000533bb466>] bus_for_each_drv+0x166/0x1e0
>>>     [<000000005bf45d75>] __device_attach+0x272/0x420
>>>     [<0000000075220311>] bus_probe_device+0x1eb/0x2a0
>>>     [<0000000015587e85>] device_add+0xbf0/0x1f90
>>>     [<0000000086901b9e>] i2c_new_client_device+0x622/0xb20
>>>     [<000000000865ca18>] new_device_store+0x1fa/0x420
>>>     [<0000000059a3d183>] dev_attr_store+0x58/0x80
>>>
>>> Fix it by remove data->dready_trig condition in probe and remove.
>>>
>>> Reported-by: Hulk Robot <hulkci@...wei.com>
>>> Fixes: a25691c1f967 ("iio: accel: kxcjk1013: allow using an external trigger")
>>> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>  
>>
>> Hmm, wouldn't the right fix be to also move the
>> iio_triggered_buffer_setup() call to inside the:
>>
>> 	if (client->irq > 0 && data->acpi_type != ACPI_SMO8500) {
>> 	}
>>
>> block ?
>>
>> Jonathan (jic23) can you take a look at this, to me it seems that having
>> a triggered buffer allocated without any triggers is not useful ?
> 
> It can use another trigger not supplied by this particular device.
> e.g. sysfs or hrtimer trigger.  This is common for cases where
> we may or may not have an irq wired and the validate_* callbacks are
> not provided (which would indicate we had to use the device's own trigger).

Ok, thank you for clarifying this.

With that resolved, this patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@...hat.com>

Regards,

Hans


>>> ---
>>>  drivers/iio/accel/kxcjk-1013.c | 5 ++---
>>>  1 file changed, 2 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/iio/accel/kxcjk-1013.c b/drivers/iio/accel/kxcjk-1013.c
>>> index a51fdd3c9b5b..24c9387c2968 100644
>>> --- a/drivers/iio/accel/kxcjk-1013.c
>>> +++ b/drivers/iio/accel/kxcjk-1013.c
>>> @@ -1595,8 +1595,7 @@ static int kxcjk1013_probe(struct i2c_client *client,
>>>  	return 0;
>>>  
>>>  err_buffer_cleanup:
>>> -	if (data->dready_trig)
>>> -		iio_triggered_buffer_cleanup(indio_dev);
>>> +	iio_triggered_buffer_cleanup(indio_dev);
>>>  err_trigger_unregister:
>>>  	if (data->dready_trig)
>>>  		iio_trigger_unregister(data->dready_trig);
>>> @@ -1618,8 +1617,8 @@ static int kxcjk1013_remove(struct i2c_client *client)
>>>  	pm_runtime_disable(&client->dev);
>>>  	pm_runtime_set_suspended(&client->dev);
>>>  
>>> +	iio_triggered_buffer_cleanup(indio_dev);
>>>  	if (data->dready_trig) {
>>> -		iio_triggered_buffer_cleanup(indio_dev);
>>>  		iio_trigger_unregister(data->dready_trig);
>>>  		iio_trigger_unregister(data->motion_trig);
>>>  	}
>>>   
>>
>