linux-kernel - Re: [PATCH v2] ata: libata: Fix memory leak for error path in ata_host

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Message-ID: <ab0b512c-2d02-4eec-876c-2340284583fe@kernel.org>
Date: Mon, 26 Aug 2024 13:02:21 +0900
From: Damien Le Moal <dlemoal@...nel.org>
To: Zheng Qixing <zhengqixing@...weicloud.com>, cassel@...nel.org
Cc: linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org,
 yukuai3@...wei.com, yi.zhang@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH v2] ata: libata: Fix memory leak for error path in
 ata_host_alloc()

On 8/26/24 11:49 AM, Zheng Qixing wrote:
> 
> 在 2024/8/23 9:10, Damien Le Moal 写道:
>> On 8/22/24 12:30 PM, Zheng Qixing wrote:
>>> From: Zheng Qixing <zhengqixing@...wei.com>
>>>
>>> In ata_host_alloc(), if ata_port_alloc(host) fails to allocate memory
>>> for a port, the allocated 'host' structure is not freed before returning
>>> from the function. This results in a potential memory leak.
>>>
>>> This patch adds a kfree(host) before the error handling code is executed
>>> to ensure that the 'host' structure is properly freed in case of an
>>> allocation failure.
>>>
>>> Signed-off-by: Zheng Qixing <zhengqixing@...wei.com>
>> This needs a Fixes tag. So I added:
>>
>> Fixes: 2623c7a5f279 ("libata: add refcounting to ata_host")
>> Cc: stable@...r.kernel.org>
>>
>> and applied to for-6.11-fixes. Thanks.
> 
> 
> Based on Niklas Cassel's suggestion, the commit message and the actual
> content of the patch do not match.
> 
> It should state "if devres_alloc(ata_devres_release, 0, GFP_KERNEL)
> fails to allocate memory" instead of "if ata_port_alloc(host) fails to allocate
> memory for a port".
> 
> Should I modify the commit message and submit a new version of the patch?

No need. I fixed it up. The commit message now is:

    ata: libata: Fix memory leak for error path in ata_host_alloc()

    In ata_host_alloc(), if devres_alloc() fails to allocate the device host
    resource data pointer, the already allocated ata_host structure is not
    freed before returning from the function. This results in a potential
    memory leak.

    Call kfree(host) before jumping to the error handling path to ensure
    that the ata_host structure is properly freed if devres_alloc() fails.

> 
> 
> Zheng Qixing
> 
> 
>>> ---
>>> Changes in v2:
>>>   - error path is wrong in v1
>>>
>>>   drivers/ata/libata-core.c | 4 +++-
>>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
>>> index e4023fc288ac..f27a18990c38 100644
>>> --- a/drivers/ata/libata-core.c
>>> +++ b/drivers/ata/libata-core.c
>>> @@ -5663,8 +5663,10 @@ struct ata_host *ata_host_alloc(struct device *dev,
>>> int n_ports)
>>>       }
>>>         dr = devres_alloc(ata_devres_release, 0, GFP_KERNEL);
>>> -    if (!dr)
>>> +    if (!dr) {
>>> +        kfree(host);
>>>           goto err_out;
>>> +    }
>>>         devres_add(dev, dr);
>>>       dev_set_drvdata(dev, host);
> 
> 

-- 
Damien Le Moal
Western Digital Research