linux-kernel - Re: [PATCH] drm/msm: Fix potential invalid ptr free

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Message-ID: <8b14864b-89fa-ef02-f025-00d7713a0bc7@linaro.org>
Date:   Thu, 16 Feb 2023 18:41:48 +0200
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Rob Clark <robdclark@...il.com>, dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...omium.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Bas Nieuwenhuizen <bas@...nieuwenhuizen.nl>,
        Jordan Crouse <jordan@...micpenguin.net>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/msm: Fix potential invalid ptr free

On 16/02/2023 01:50, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
> 
> The error path cleanup expects that chain and syncobj are either NULL or
> valid pointers.  But post_deps was not allocated with __GFP_ZERO.
> 
> Fixes: ab723b7a992a ("drm/msm: Add syncobj support.")
> Signed-off-by: Rob Clark <robdclark@...omium.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

This makes me want to rewrite the ab723b7a992a ("drm/msm: Add syncobj 
support.") in the usual explicit-error-path way. WDYT?

> ---
>   drivers/gpu/drm/msm/msm_gem_submit.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> index 6503220e5a4b..e4d13540300e 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -640,8 +640,8 @@ static struct msm_submit_post_dep *msm_parse_post_deps(struct drm_device *dev,
>   	int ret = 0;
>   	uint32_t i, j;
>   
> -	post_deps = kmalloc_array(nr_syncobjs, sizeof(*post_deps),
> -	                          GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
> +	post_deps = kcalloc(nr_syncobjs, sizeof(*post_deps),
> +			    GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
>   	if (!post_deps)
>   		return ERR_PTR(-ENOMEM);
>   
> @@ -656,7 +656,6 @@ static struct msm_submit_post_dep *msm_parse_post_deps(struct drm_device *dev,
>   		}
>   
>   		post_deps[i].point = syncobj_desc.point;
> -		post_deps[i].chain = NULL;
>   
>   		if (syncobj_desc.flags) {
>   			ret = -EINVAL;

-- 
With best wishes
Dmitry