linux-kernel - Re: [PATCH] vfio/platform: Remove unnecessary free in vfio_set

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Message-ID: <20240112083447.750ad1c6.alex.williamson@redhat.com>
Date: Fri, 12 Jan 2024 08:34:47 -0700
From: Alex Williamson <alex.williamson@...hat.com>
To: Kunwu Chan <chentao@...inos.cn>
Cc: eric.auger@...hat.com, a.motakis@...tualopensystems.com,
 b.reynal@...tualopensystems.com, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vfio/platform: Remove unnecessary free in
 vfio_set_trigger

On Fri, 12 Jan 2024 14:41:07 +0800
Kunwu Chan <chentao@...inos.cn> wrote:

> commit 57f972e2b341 ("vfio/platform: trigger an interrupt via eventfd")
> add 'name' as member for vfio_platform_irq,it's initialed by kasprintf,
> so there is no need to free it before initializing.

What?!  Just look at the call path where vfio_set_trigger() is called
with a valid fd and existing trigger.  This change would leak irq->name
as it's reallocated via kasprintf().  Thanks,

Alex
 
> Fixes: 57f972e2b341 ("vfio/platform: trigger an interrupt via eventfd")
> Signed-off-by: Kunwu Chan <chentao@...inos.cn>
> ---
>  drivers/vfio/platform/vfio_platform_irq.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index 61a1bfb68ac7..5e3fd1926366 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -179,7 +179,6 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
>  	if (irq->trigger) {
>  		irq_clear_status_flags(irq->hwirq, IRQ_NOAUTOEN);
>  		free_irq(irq->hwirq, irq);
> -		kfree(irq->name);
>  		eventfd_ctx_put(irq->trigger);
>  		irq->trigger = NULL;
>  	}