Re: [PATCH v2] platform/x86: ISST: fix use-after-free in tpmi_sst_dev_remove()

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 5/17/24 4:49 PM, Harshit Mogalapalli wrote:
> In tpmi_sst_dev_remove(), tpmi_sst is dereferenced after being freed.
> Fix this by reordering the kfree() post the dereference.
> 
> Fixes: 9d1d36268f3d ("platform/x86: ISST: Support partitioned systems")
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>

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.

I will include this patch in my next fixes pull-req to Linus
for the current kernel development cycle.

Regards,

Hans




> ---
> v1->v2: Add R.B from Hans and fix commit message wrapping to 75 chars.
> This is found by smatch and only compile tested.
> ---
>  drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> index 7bac7841ff0a..7fa360073f6e 100644
> --- a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> +++ b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
> @@ -1610,8 +1610,8 @@ void tpmi_sst_dev_remove(struct auxiliary_device *auxdev)
>  	tpmi_sst->partition_mask_current &= ~BIT(plat_info->partition);
>  	/* Free the package instance when the all partitions are removed */
>  	if (!tpmi_sst->partition_mask_current) {
> -		kfree(tpmi_sst);
>  		isst_common.sst_inst[tpmi_sst->package_id] = NULL;
> +		kfree(tpmi_sst);
>  	}
>  	mutex_unlock(&isst_tpmi_dev_lock);
>  }