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From: Biju Das <biju.das.jz@bp.renesas.com>
To: Steven Price <steven.price@arm.com>,
	Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>
Cc: "dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Pavel Machek <pavel@denx.de>
Subject: RE: [PATCH] drm/of: free the iterator object on failure
Date: Mon, 12 Jul 2021 16:03:55 +0000	[thread overview]
Message-ID: <OS0PR01MB592294867B449F855496337186159@OS0PR01MB5922.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <20210712155758.48286-1-steven.price@arm.com>

+ Pavel

> -----Original Message-----
> From: Steven Price <steven.price@arm.com>
> Sent: 12 July 2021 16:58
> To: Daniel Vetter <daniel@ffwll.ch>; David Airlie <airlied@linux.ie>;
> Maarten Lankhorst <maarten.lankhorst@linux.intel.com>; Maxime Ripard
> <mripard@kernel.org>; Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Steven Price <steven.price@arm.com>; dri-devel@lists.freedesktop.org;
> linux-kernel@vger.kernel.org; Biju Das <biju.das.jz@bp.renesas.com>;
> Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Subject: [PATCH] drm/of: free the iterator object on failure
> 
> When bailing out due to the sanity check the iterator value needs to be
> freed because the early return prevents for_each_child_of_node() from
> doing the dereference itself.
> 
> Fixes: 4ee48cc5586b ("drm: of: Fix double-free bug")
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
>  drivers/gpu/drm/drm_of.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> Daniel's email[1] made me take a look at this function and it appears that
> for_each_child_of_node()'s interface had caused a bad bug fix due to the
> hidden reference counting in the iterator.
> 
> [1]
> https://jpn01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.ker
> nel.org%2Fr%2FYOxQ5TbkNrqCGBDJ%2540phenom.ffwll.local&amp;data=04%7C01%7Cb
> iju.das.jz%40bp.renesas.com%7Cb0570b66e03a43fb8fa008d9454dddaa%7C53d82571d
> a1947e49cb4625a166a4a2a%7C0%7C0%7C637617023006562683%7CUnknown%7CTWFpbGZsb
> 3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C10
> 00&amp;sdata=cQICPYJzmgNkFsNw1wMH9Or73rohnCCGH1DrUg3hvhw%3D&amp;reserved=0
> 
> diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c index
> 197c57477344..997b8827fed2 100644
> --- a/drivers/gpu/drm/drm_of.c
> +++ b/drivers/gpu/drm/drm_of.c
> @@ -331,8 +331,10 @@ static int drm_of_lvds_get_remote_pixels_type(
>  		 * configurations by passing the endpoints explicitly to
>  		 * drm_of_lvds_get_dual_link_pixel_order().
>  		 */
> -		if (!current_pt || pixels_type != current_pt)
> +		if (!current_pt || pixels_type != current_pt) {
> +			of_node_put(endpoint);
>  			return -EINVAL;
> +		}
>  	}
> 
>  	return pixels_type;
> --
> 2.20.1


  reply	other threads:[~2021-07-12 16:04 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-12 15:57 Steven Price
2021-07-12 16:03 ` Biju Das [this message]
2021-07-12 16:50 ` Laurent Pinchart
2021-07-12 21:31   ` Steven Price
2021-07-12 21:55     ` Laurent Pinchart
2021-07-13 16:16       ` Steven Price
2021-07-14  8:35         ` Laurent Pinchart
2021-07-14 14:33 ` [PATCH v2] " Steven Price
2021-07-14 15:26   ` Laurent Pinchart
2021-07-15 10:32     ` Steven Price

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