From: Ruan Jinjie <ruanjinjie@huawei.com>
To: Russ Weight <russell.h.weight@intel.com>, <mdf@kernel.org>,
<hao.wu@intel.com>, <yilun.xu@intel.com>, <trix@redhat.com>,
<linux-fpga@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RESEND] fpga: region: Fix possible memory leak in fpga_region_register_full()
Date: Sat, 7 Oct 2023 17:15:06 +0800 [thread overview]
Message-ID: <78adf4cf-e43d-fa1b-1d65-43c25e0cba6b@huawei.com> (raw)
In-Reply-To: <9842e1cc-3e61-3759-30f0-b4968622e0a7@intel.com>
On 2023/9/28 23:45, Russ Weight wrote:
>
>
> On 9/28/23 02:16, Jinjie Ruan wrote:
>> If device_register() fails in fpga_region_register_full(), the region
>> allocated by kzalloc() and the id allocated by ida_alloc() also need be
>> freed otherwise will cause memory leak.
>>
>> Fixes: 8886a579744f ("fpga: region: Use standard dev_release for class driver")
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>> drivers/fpga/fpga-region.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
>> index b364a929425c..9dc6314976ef 100644
>> --- a/drivers/fpga/fpga-region.c
>> +++ b/drivers/fpga/fpga-region.c
>> @@ -228,12 +228,13 @@ fpga_region_register_full(struct device *parent, const struct fpga_region_info *
>>
>> ret = device_register(®ion->dev);
>
> The comments for device_register() say:
>
> * NOTE: _Never_ directly free @dev after calling this function, even
> * if it returned an error! Always use put_device() to give up the
> * reference initialized in this function instead.
>
> Note that dev is embedded in the region structure, so freeing region
> means freeing dev.
>
> The expectation is that after device_register() has been called, even
> if it returns an error, put_device() is used to lower the reference
> count. When the reference count is zero, the fpga_region_dev_release()
> function is called. fpga_region_dev_release() frees calls ida_free()
> and frees the region.
Right!
>
> Have you observed different behavior? Do you have evidence of a memory
> leak?
I have noticed a memory leak in using fpga_region_register_full() in
fpga-region-test.c. I'll send the patch sooner.
>
> Thanks,
> - Russ
>
>> if (ret) {
>> - put_device(®ion->dev);
>> - return ERR_PTR(ret);
>> + goto err_put_device;
>> }
>>
>> return region;
>>
>> +err_put_device:
>> + put_device(®ion->dev);
>> err_remove:
>> ida_free(&fpga_region_ida, id);
>> err_free:
>
prev parent reply other threads:[~2023-10-07 9:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-28 9:16 [PATCH RESEND] fpga: region: Fix possible memory leak in fpga_region_register_full() Jinjie Ruan
2023-09-28 14:02 ` Xu Yilun
2023-09-28 15:45 ` Russ Weight
2023-10-07 9:15 ` Ruan Jinjie [this message]
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