linux-kernel - Re: [PATCH linux-next v2 1/3] platform/x86/intel/tpmi: Fix double free in tpmi_create

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Date:   Fri, 17 Mar 2023 09:51:36 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Dongliang Mu <dzm91@...t.edu.cn>,
        srinivas pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Mark Gross <markgross@...nel.org>
Cc:     platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH linux-next v2 1/3] platform/x86/intel/tpmi: Fix double
 free in tpmi_create_device()

Hi,

On 3/17/23 02:28, Dongliang Mu wrote:
> 
> On 2023/3/17 02:18, srinivas pandruvada wrote:
>> Hi Hans,
>>
>> On Thu, 2023-03-16 at 15:25 +0100, Hans de Goede wrote:
>>> Hi,
>>>
>>> On 3/9/23 05:01, Dongliang Mu wrote:
>>>> The previous commit 6a192c0cbf38 ("platform/x86/intel/tpmi: Fix
>>>> double free reported by Smatch") incorrectly handle the
>>>> deallocation of
>>>> res variable. As shown in the comment, intel_vsec_add_aux handles
>>>> all
>>>> the deallocation of res and feature_vsec_dev. Therefore, kfree(res)
>>>> can
>>>> still cause double free if intel_vsec_add_aux returns error.
>>>>
>>>> Fix this by adjusting the error handling part in
>>>> tpmi_create_device,
>>>> following the function intel_vsec_add_dev.
>>>>
>>>> Fixes: 6a192c0cbf38 ("platform/x86/intel/tpmi: Fix double free
>>>> reported by Smatch")
>>>> Signed-off-by: Dongliang Mu <dzm91@...t.edu.cn>
>> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
>>
>>> IIRC then after this v2 was posted I still saw some comments on the
>>> original v1 which was not posted on the list. Without the v1 comments
>>> being on the list and this archived, I have lost track of what the
>>> status of these patches is.
>>>
>>> Srinivas, can you let me know if I should merge these, or if more
>>> changes are necessary ?
>>>
>>>  From the off-list discussion of v1 I got the impression more changes
>>> are necessary, but I'm not sure.
>> I was looking for changes submitted by the following patch
>> "
>> [PATCH linux-next v2 3/3] drivers/platform/x86/intel: fix a memory leak
>> in intel_vsec_add_aux
>> "
>>
>> Since I was not copied on this, I was unaware. So I was requesting this
>> change.
>>
>> Thanks,
>> Srinivas
> 
> Hi Srinivas and Hans,
> 
> How about folding these three patches into one patch and resend a v3 patch?
> 
> This will get all people together and avoid the previous embarrassing sitation.

If I understand things correctly then patch 1/3 needs 3/3 to function correctly, right ?

I would not fold them together, smaller patches are easier to review / understand, but maybe change the order and put patch 3/3 first? (so make it 1/3) ?

I can even do that when applying if you agree that is the better order.

Regards,

Hans



>>>> ---
>>>>   drivers/platform/x86/intel/tpmi.c | 17 ++++-------------
>>>>   1 file changed, 4 insertions(+), 13 deletions(-)
>>>>
>>>> diff --git a/drivers/platform/x86/intel/tpmi.c
>>>> b/drivers/platform/x86/intel/tpmi.c
>>>> index c999732b0f1e..882fe5e4763f 100644
>>>> --- a/drivers/platform/x86/intel/tpmi.c
>>>> +++ b/drivers/platform/x86/intel/tpmi.c
>>>> @@ -215,8 +215,8 @@ static int tpmi_create_device(struct
>>>> intel_tpmi_info *tpmi_info,
>>>>            feature_vsec_dev = kzalloc(sizeof(*feature_vsec_dev),
>>>> GFP_KERNEL);
>>>>          if (!feature_vsec_dev) {
>>>> -               ret = -ENOMEM;
>>>> -               goto free_res;
>>>> +               kfree(res);
>>>> +               return -ENOMEM;
>>>>          }
>>>>            snprintf(feature_id_name, sizeof(feature_id_name), "tpmi-
>>>> %s", name);
>>>> @@ -242,17 +242,8 @@ static int tpmi_create_device(struct
>>>> intel_tpmi_info *tpmi_info,
>>>>           * feature_vsec_dev memory is also freed as part of device
>>>>           * delete.
>>>>           */
>>>> -       ret = intel_vsec_add_aux(vsec_dev->pcidev, &vsec_dev-
>>>>> auxdev.dev,
>>>> -                                feature_vsec_dev,
>>>> feature_id_name);
>>>> -       if (ret)
>>>> -               goto free_res;
>>>> -
>>>> -       return 0;
>>>> -
>>>> -free_res:
>>>> -       kfree(res);
>>>> -
>>>> -       return ret;
>>>> +       return intel_vsec_add_aux(vsec_dev->pcidev, &vsec_dev-
>>>>> auxdev.dev,
>>>> +                                 feature_vsec_dev,
>>>> feature_id_name);
>>>>   }
>>>>     static int tpmi_create_devices(struct intel_tpmi_info *tpmi_info)