|
 |
007868a |
From 4bef1a1d32e29b68855616020dbff574b9cda08f Mon Sep 17 00:00:00 2001
|
|
|
007868a |
From: Robin Watts <Robin.Watts@artifex.com>
|
|
|
007868a |
Date: Thu, 29 Dec 2016 15:57:43 +0000
|
|
|
007868a |
Subject: [PATCH] Bug 697453: Avoid divide by 0 in scan conversion code.
|
|
|
007868a |
|
|
|
007868a |
Arithmetic overflow due to extreme values in the scan conversion
|
|
|
007868a |
code can cause a division by 0.
|
|
|
007868a |
|
|
|
007868a |
Avoid this with a simple extra check.
|
|
|
007868a |
|
|
|
007868a |
dx_old=cf814d81
|
|
|
007868a |
endp->x_next=b0e859b9
|
|
|
007868a |
alp->x_next=8069a73a
|
|
|
007868a |
|
|
|
007868a |
leads to dx_den = 0
|
|
|
007868a |
---
|
|
|
007868a |
base/gxfill.c | 4 ++--
|
|
|
007868a |
1 file changed, 2 insertions(+), 2 deletions(-)
|
|
|
007868a |
|
|
|
007868a |
diff --git a/base/gxfill.c b/base/gxfill.c
|
|
|
007868a |
index 99196c0..2f81bb0 100644
|
|
|
007868a |
--- a/base/gxfill.c
|
|
|
007868a |
+++ b/base/gxfill.c
|
|
|
007868a |
@@ -1741,7 +1741,7 @@ intersect(active_line *endp, active_line *alp, fixed y, fixed y1, fixed *p_y_new
|
|
|
007868a |
fixed dx_old = alp->x_current - endp->x_current;
|
|
|
007868a |
fixed dx_den = dx_old + endp->x_next - alp->x_next;
|
|
|
007868a |
|
|
|
007868a |
- if (dx_den <= dx_old)
|
|
|
007868a |
+ if (dx_den <= dx_old || dx_den == 0)
|
|
|
007868a |
return false; /* Intersection isn't possible. */
|
|
|
007868a |
dy = y1 - y;
|
|
|
007868a |
if_debug3('F', "[F]cross: dy=%g, dx_old=%g, dx_new=%g\n",
|
|
|
007868a |
@@ -1750,7 +1750,7 @@ intersect(active_line *endp, active_line *alp, fixed y, fixed y1, fixed *p_y_new
|
|
|
007868a |
/* Do the computation in single precision */
|
|
|
007868a |
/* if the values are small enough. */
|
|
|
007868a |
y_new =
|
|
|
007868a |
- ((dy | dx_old) < 1L << (size_of(fixed) * 4 - 1) ?
|
|
|
007868a |
+ (((ufixed)(dy | dx_old)) < (1L << (size_of(fixed) * 4 - 1)) ?
|
|
|
007868a |
dy * dx_old / dx_den :
|
|
|
007868a |
(INCR_EXPR(mq_cross), fixed_mult_quo(dy, dx_old, dx_den)))
|
|
|
007868a |
+ y;
|
|
|
007868a |
--
|
|
|
007868a |
2.9.3
|
|
|
007868a |
|