linux-kernel - Re: [PATCH 1/1] drm/hyperv: Fix address space leak when Hyper-V DRM device is removed

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Message-ID: <445e33f1-280a-436d-8f9a-c94d16c17efd@suse.de>
Date: Tue, 11 Feb 2025 08:34:37 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: mhklinux@...look.com, drawat.floss@...il.com,
 maarten.lankhorst@...ux.intel.com, mripard@...nel.org, airlied@...il.com,
 simona@...ll.ch, christophe.jaillet@...adoo.fr, ssengar@...ux.microsoft.com,
 wei.liu@...nel.org
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 linux-hyperv@...r.kernel.org
Subject: Re: [PATCH 1/1] drm/hyperv: Fix address space leak when Hyper-V DRM
 device is removed

Hi

Am 10.02.25 um 20:34 schrieb mhkelley58@...il.com:
> From: Michael Kelley <mhklinux@...look.com>
>
> When a Hyper-V DRM device is probed, the driver allocates MMIO space for
> the vram, and maps it cacheable. If the device removed, or in the error
> path for device probing, the MMIO space is released but no unmap is done.
> Consequently the kernel address space for the mapping is leaked.
>
> Fix this by adding iounmap() calls in the device removal path, and in the
> error path during device probing.

Could this driver use devm_ helpers for iomap operations? That should 
fix the issue automatically.

Best regards
Thomas

>
> Fixes: f1f63cbb705d ("drm/hyperv: Fix an error handling path in hyperv_vmbus_probe()")
> Fixes: a0ab5abced55 ("drm/hyperv : Removing the restruction of VRAM allocation with PCI bar size")
> Signed-off-by: Michael Kelley <mhklinux@...look.com>
> ---
>   drivers/gpu/drm/hyperv/hyperv_drm_drv.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> index e0953777a206..b491827941f1 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> @@ -156,6 +156,7 @@ static int hyperv_vmbus_probe(struct hv_device *hdev,
>   	return 0;
>   
>   err_free_mmio:
> +	iounmap(hv->vram);
>   	vmbus_free_mmio(hv->mem->start, hv->fb_size);
>   err_vmbus_close:
>   	vmbus_close(hdev->channel);
> @@ -174,6 +175,7 @@ static void hyperv_vmbus_remove(struct hv_device *hdev)
>   	vmbus_close(hdev->channel);
>   	hv_set_drvdata(hdev, NULL);
>   
> +	iounmap(hv->vram);
>   	vmbus_free_mmio(hv->mem->start, hv->fb_size);
>   }
>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)