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From patchwork Wed Oct 2 13:47:54 2013
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Subject: exa: only draw valid trapezoids
From: Maarten Lankhorst <maarten.lankhorst@canonical.com>
X-Patchwork-Id: 14769
Message-Id: <524C240A.9010607@canonical.com>
To: "X.Org Devel List" <xorg-devel@lists.freedesktop.org>
Date: Wed, 02 Oct 2013 15:47:54 +0200
Fixes freedesktop.org bug https://bugs.freedesktop.org/show_bug.cgi?id=67484
If t->bottom is close to MIN_INT, removing top can wraparound, so do the check properly.
A similar fix should also be applied to pixman.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
---
diff --git a/exa/exa_render.c b/exa/exa_render.c
index 172e2b5..807eeba 100644
--- a/exa/exa_render.c
+++ b/exa/exa_render.c
@@ -1141,7 +1141,8 @@ exaTrapezoids(CARD8 op, PicturePtr pSrc, PicturePtr pDst,
exaPrepareAccess(pPicture->pDrawable, EXA_PREPARE_DEST);
for (; ntrap; ntrap--, traps++)
- (*ps->RasterizeTrapezoid) (pPicture, traps, -bounds.x1, -bounds.y1);
+ if (xTrapezoidValid(traps))
+ (*ps->RasterizeTrapezoid) (pPicture, traps, -bounds.x1, -bounds.y1);
exaFinishAccess(pPicture->pDrawable, EXA_PREPARE_DEST);
xRel = bounds.x1 + xSrc - xDst;
diff --git a/render/picture.h b/render/picture.h
index c85353a..fcd6401 100644
--- a/render/picture.h
+++ b/render/picture.h
@@ -211,7 +211,7 @@ typedef pixman_fixed_t xFixed;
/* whether 't' is a well defined not obviously empty trapezoid */
#define xTrapezoidValid(t) ((t)->left.p1.y != (t)->left.p2.y && \
(t)->right.p1.y != (t)->right.p2.y && \
- (int) ((t)->bottom - (t)->top) > 0)
+ ((t)->bottom > (t)->top))
/*
* Standard NTSC luminance conversions:
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