linux-kernel - Re: [PATCH] driver core: Fix possible memory leak in device_link

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Date:   Fri, 8 Oct 2021 09:53:09 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     Saravana Kannan <saravanak@...gle.com>
CC:     <linux-kernel@...r.kernel.org>, <rafael@...nel.org>,
        <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] driver core: Fix possible memory leak in
 device_link_add()

Hi,

On 2021/10/2 4:47, Saravana Kannan wrote:
> On Thu, Sep 30, 2021 at 1:52 AM Yang Yingliang <yangyingliang@...wei.com> wrote:
>> I got memory leak as follows:
>>
>> unreferenced object 0xffff88801f0b2200 (size 64):
>>    comm "i2c-lis2hh12-21", pid 5455, jiffies 4294944606 (age 15.224s)
>>    hex dump (first 32 bytes):
>>      72 65 67 75 6c 61 74 6f 72 3a 72 65 67 75 6c 61  regulator:regula
>>      74 6f 72 2e 30 2d 2d 69 32 63 3a 31 2d 30 30 31  tor.0--i2c:1-001
>>    backtrace:
>>      [<00000000bf5b0c3b>] __kmalloc_track_caller+0x19f/0x3a0
>>      [<0000000050da42d9>] kvasprintf+0xb5/0x150
>>      [<000000004bbbed13>] kvasprintf_const+0x60/0x190
>>      [<00000000cdac7480>] kobject_set_name_vargs+0x56/0x150
>>      [<00000000bf83f8e8>] dev_set_name+0xc0/0x100
>>      [<00000000cc1cf7e3>] device_link_add+0x6b4/0x17c0
>>      [<000000009db9faed>] _regulator_get+0x297/0x680
>>      [<00000000845e7f2b>] _devm_regulator_get+0x5b/0xe0
>>      [<000000003958ee25>] st_sensors_power_enable+0x71/0x1b0 [st_sensors]
>>      [<000000005f450f52>] st_accel_i2c_probe+0xd9/0x150 [st_accel_i2c]
>>      [<00000000b5f2ab33>] i2c_device_probe+0x4d8/0xbe0
>>      [<0000000070fb977b>] really_probe+0x299/0xc30
>>      [<0000000088e226ce>] __driver_probe_device+0x357/0x500
>>      [<00000000c21dda32>] driver_probe_device+0x4e/0x140
>>      [<000000004e650441>] __device_attach_driver+0x257/0x340
>>      [<00000000cf1891b8>] bus_for_each_drv+0x166/0x1e0
>>
>> When device_register() returns an error, the name allocated in dev_set_name()
>> will be leaked, the put_device() should be used instead of kfree() to give up
>> the device reference, then the name will be freed in kobject_cleanup() and the
>> references of consumer and supplier will be decreased in device_link_release_fn().
>>
>> Fixes: 287905e68dd2 ("driver core: Expose device link details in sysfs")
>> Reported-by: Hulk Robot <hulkci@...wei.com>
>> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
>> ---
>>   drivers/base/core.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/base/core.c b/drivers/base/core.c
>> index e65dd803a453..4a123e58711f 100644
>> --- a/drivers/base/core.c
>> +++ b/drivers/base/core.c
>> @@ -809,9 +809,7 @@ struct device_link *device_link_add(struct device *consumer,
>>                       dev_bus_name(supplier), dev_name(supplier),
>>                       dev_bus_name(consumer), dev_name(consumer));
>>          if (device_register(&link->link_dev)) {
>> -               put_device(consumer);
>> -               put_device(supplier);
>> -               kfree(link);
>> +               put_device(&link->link_dev);
>>                  link = NULL;
>>                  goto out;
>>          }
>> --
>> 2.25.1
>>
> Thanks for the fix!
>
> Reviewed-by: Saravana Kannan <saravanak@...gle.com>
>
> Btw, can you also let us know why the device_register() is failing? It
> really shouldn't be failing.
I inject fault in device_add().
>
> -Saravana
> .