[PATCH] drm/vmwgfx: Use correct vmw_legacy_display_unit pointer

[PATCH] drm/vmwgfx: Use correct vmw_legacy_display_unit pointer

[Dan Carpenter]

The "entry" pointer is an offset from the list head and it doesn't
point to a valid vmw_legacy_display_unit struct.  Presumably the
intent was to point to the last entry.

Also the "i++" wasn't used so I have removed that as well.

Fixes: d7e1958dbe4a ("drm/vmwgfx: Support older hardware.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
From static analysis.  Not tested.  This bug celebrated its tenth
birthday last month.  :)

 drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c
index 16dafff5cab1..009f1742bed5 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c
@@ -81,7 +81,7 @@ static int vmw_ldu_commit_list(struct vmw_private *dev_priv)
 	struct vmw_legacy_display_unit *entry;
 	struct drm_framebuffer *fb = NULL;
 	struct drm_crtc *crtc = NULL;
-	int i = 0;
+	int i;
 
 	/* If there is no display topology the host just assumes
 	 * that the guest will set the same layout as the host.
@@ -92,12 +92,11 @@ static int vmw_ldu_commit_list(struct vmw_private *dev_priv)
 			crtc = &entry->base.crtc;
 			w = max(w, crtc->x + crtc->mode.hdisplay);
 			h = max(h, crtc->y + crtc->mode.vdisplay);
-			i++;
 		}
 
 		if (crtc = NULL)
 			return 0;
-		fb = entry->base.crtc.primary->state->fb;
+		fb = crtc->primary->state->fb;
 
 		return vmw_kms_write_svga(dev_priv, w, h, fb->pitches[0],
 					  fb->format->cpp[0] * 8,
-- 
2.27.0

Re: [PATCH] drm/vmwgfx: Use correct vmw_legacy_display_unit pointer

[Roland Scheidegger]

Sorry for the delay, finally got time to look at this, seems all correct
to me, thanks. Applied to our vmvgfx-next tree. (I do wonder how this
somehow was supposed to work for all this time...)

Roland

Am 26.06.20 um 12:34 schrieb Dan Carpenter:
> The "entry" pointer is an offset from the list head and it doesn't
> point to a valid vmw_legacy_display_unit struct.  Presumably the
> intent was to point to the last entry.
> 
> Also the "i++" wasn't used so I have removed that as well.
> 
> Fixes: d7e1958dbe4a ("drm/vmwgfx: Support older hardware.")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> From static analysis.  Not tested.  This bug celebrated its tenth
> birthday last month.  :)
> 
>  drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c
> index 16dafff5cab1..009f1742bed5 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ldu.c
> @@ -81,7 +81,7 @@ static int vmw_ldu_commit_list(struct vmw_private *dev_priv)
>  	struct vmw_legacy_display_unit *entry;
>  	struct drm_framebuffer *fb = NULL;
>  	struct drm_crtc *crtc = NULL;
> -	int i = 0;
> +	int i;
>  
>  	/* If there is no display topology the host just assumes
>  	 * that the guest will set the same layout as the host.
> @@ -92,12 +92,11 @@ static int vmw_ldu_commit_list(struct vmw_private *dev_priv)
>  			crtc = &entry->base.crtc;
>  			w = max(w, crtc->x + crtc->mode.hdisplay);
>  			h = max(h, crtc->y + crtc->mode.vdisplay);
> -			i++;
>  		}
>  
>  		if (crtc = NULL)
>  			return 0;
> -		fb = entry->base.crtc.primary->state->fb;
> +		fb = crtc->primary->state->fb;
>  
>  		return vmw_kms_write_svga(dev_priv, w, h, fb->pitches[0],
>  					  fb->format->cpp[0] * 8,
>