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

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Date:   Mon, 20 Mar 2023 11:32:44 +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 3/9/23 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>

Note this patch causes the following compiler warnings:

  CC [M]  drivers/platform/x86/intel/tpmi.o
drivers/platform/x86/intel/tpmi.c: In function ‘tpmi_create_device’:
drivers/platform/x86/intel/tpmi.c:206:13: warning: unused variable ‘ret’ [-Wunused-variable]
  206 |         int ret, i;
      |             ^~~

I have fixed this and squashed the fix into the patch while applying it,
so there is no need to send a new version:

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

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)