linux-kernel - Re: [PATCH v4 1/8] drm/msm/dpu: don't mix devm and drmm functions

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Message-ID: <20251228173503.GA16606@pendragon.ideasonboard.com>
Date: Sun, 28 Dec 2025 19:35:03 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Jani Nikula <jani.nikula@...ux.intel.com>,
	Harry Wentland <harry.wentland@....com>,
	Leo Li <sunpeng.li@....com>, Rodrigo Siqueira <siqueira@...lia.com>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Liviu Dudau <liviu.dudau@....com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Rob Clark <robin.clark@....qualcomm.com>,
	Dmitry Baryshkov <lumag@...nel.org>,
	Abhinav Kumar <abhinav.kumar@...ux.dev>,
	Jessica Zhang <jessica.zhang@....qualcomm.com>,
	Sean Paul <sean@...rly.run>,
	Marijn Suijten <marijn.suijten@...ainline.org>,
	Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>,
	Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>,
	Dave Stevenson <dave.stevenson@...pberrypi.com>,
	Maíra Canal <mcanal@...lia.com>,
	Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	Jessica Zhang <jesszhan0024@...il.com>,
	Louis Chauvet <louis.chauvet@...tlin.com>,
	amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	freedreno@...ts.freedesktop.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v4 1/8] drm/msm/dpu: don't mix devm and drmm functions

On Sun, Dec 28, 2025 at 07:21:33PM +0200, Dmitry Baryshkov wrote:
> Mixing devm and drmm functions can result in a use-after-free errors.
> Change dpu_writeback_init() to use drmm_

The commit message should explain what the problem is. "can result" is
very vague.

> Fixes: 0b37ac63fc9d ("drm/msm/dpu: use drmm_writeback_connector_init()")
> Reported-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> Closes: https://lore.kernel.org/r/78c764b8-44cf-4db5-88e7-807a85954518@wanadoo.fr
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
> index 7545c0293efb..6f2370c9dd98 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
> @@ -5,6 +5,7 @@
>  
>  #include <drm/drm_edid.h>
>  #include <drm/drm_framebuffer.h>
> +#include <drm/drm_managed.h>
>  
>  #include "dpu_writeback.h"
>  
> @@ -125,7 +126,7 @@ int dpu_writeback_init(struct drm_device *dev, struct drm_encoder *enc,
>  	struct dpu_wb_connector *dpu_wb_conn;
>  	int rc = 0;
>  
> -	dpu_wb_conn = devm_kzalloc(dev->dev, sizeof(*dpu_wb_conn), GFP_KERNEL);
> +	dpu_wb_conn = drmm_kzalloc(dev, sizeof(*dpu_wb_conn), GFP_KERNEL);
>  	if (!dpu_wb_conn)
>  		return -ENOMEM;
>  

-- 
Regards,

Laurent Pinchart