linux-kernel - Re: [PATCH v2] drm/msm/dpu: Fix uninitialized variable

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Message-ID: <zj7sqsg3ruev4akl5paedsg65qyh53iddqvssrye2pjtfofs3q@u4g3kevpl2jn>
Date: Tue, 11 Feb 2025 10:23:54 +0100
From: Marijn Suijten <marijn.suijten@...ainline.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc: Ethan Carter Edwards <ethan@...ancedwards.com>, 
	Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>, 
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Simona Vetter <simona@...ll.ch>, linux-arm-msm@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] drm/msm/dpu: Fix uninitialized variable

On 2025-02-10 14:14:14, Abhinav Kumar wrote:
> 
> 
> On 2/9/2025 7:51 PM, Ethan Carter Edwards wrote:
> > There is a possibility for an uninitialized *ret* variable to be
> > returned in some code paths.
> > 
> > Fix this by initializing *ret* to 0.
> > 
> > Addresses-Coverity-ID: 1642546 ("Uninitialized scalar variable")
> > Fixes: 774bcfb731765d ("drm/msm/dpu: add support for virtual planes")
> > Signed-off-by: Ethan Carter Edwards <ethan@...ancedwards.com>
> > ---
> > Changes in v2:
> > - Return explicit 0 when no error occurs
> > - Add hardening mailing lists
> > - Link to v1: https://lore.kernel.org/r/20250209-dpu-v1-1-0db666884f70@ethancedwards.com
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 7 +++----
> >   1 file changed, 3 insertions(+), 4 deletions(-)
> > 
> 
> Thanks for your patch, this was addressed with
> 
> https://patchwork.freedesktop.org/patch/631567/ but since this is better 
> I am fine with this, will pick this one up

The `return 0;` in this patch should certainly fix this issue entirely and we
don't need to inline the `int ret` for that, which I think is against mixed
declaration rules anyway?

As far as I understand that's what Dmitry suggested in v1, but he r-b'd it in
this form.  Dmitry, was that intended?

- Marijn

> Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> 
> 
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> > index 098abc2c0003cde90ce6219c97ee18fa055a92a5..af3e541f60c303eb5212524e877129359b5ca98c 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> > @@ -1164,7 +1164,6 @@ int dpu_assign_plane_resources(struct dpu_global_state *global_state,
> >   			       unsigned int num_planes)
> >   {
> >   	unsigned int i;
> > -	int ret;
> >   
> >   	for (i = 0; i < num_planes; i++) {
> >   		struct drm_plane_state *plane_state = states[i];
> > @@ -1173,13 +1172,13 @@ int dpu_assign_plane_resources(struct dpu_global_state *global_state,
> >   		    !plane_state->visible)
> >   			continue;
> >   
> > -		ret = dpu_plane_virtual_assign_resources(crtc, global_state,
> > +		int ret = dpu_plane_virtual_assign_resources(crtc, global_state,
> >   							 state, plane_state);
> >   		if (ret)
> > -			break;
> > +			return ret;
> >   	}
> >   
> > -	return ret;
> > +	return 0;
> >   }
> >   
> >   static void dpu_plane_flush_csc(struct dpu_plane *pdpu, struct dpu_sw_pipe *pipe)
> > 
> > ---
> > base-commit: a64dcfb451e254085a7daee5fe51bf22959d52d3
> > change-id: 20250209-dpu-c3fac78fc617
> > 
> > Best regards,
>