| From 4bef1a1d32e29b68855616020dbff574b9cda08f Mon Sep 17 00:00:00 2001 |
| From: Robin Watts <Robin.Watts@artifex.com> |
| Date: Thu, 29 Dec 2016 15:57:43 +0000 |
| Subject: [PATCH] Bug 697453: Avoid divide by 0 in scan conversion code. |
| |
| Arithmetic overflow due to extreme values in the scan conversion |
| code can cause a division by 0. |
| |
| Avoid this with a simple extra check. |
| |
| dx_old=cf814d81 |
| endp->x_next=b0e859b9 |
| alp->x_next=8069a73a |
| |
| leads to dx_den = 0 |
| |
| Upstream-Status: Backport |
| CVE: CVE-2016-10219 |
| |
| Signed-off-by: Catalin Enache <catalin.enache@windriver.com> |
| --- |
| base/gxfill.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| diff --git a/base/gxfill.c b/base/gxfill.c |
| index 99196c0..2f81bb0 100644 |
| --- a/base/gxfill.c |
| +++ b/base/gxfill.c |
| @@ -1741,7 +1741,7 @@ intersect(active_line *endp, active_line *alp, fixed y, fixed y1, fixed *p_y_new |
| fixed dx_old = alp->x_current - endp->x_current; |
| fixed dx_den = dx_old + endp->x_next - alp->x_next; |
| |
| - if (dx_den <= dx_old) |
| + if (dx_den <= dx_old || dx_den == 0) |
| return false; /* Intersection isn't possible. */ |
| dy = y1 - y; |
| if_debug3('F', "[F]cross: dy=%g, dx_old=%g, dx_new=%g\n", |
| @@ -1750,7 +1750,7 @@ intersect(active_line *endp, active_line *alp, fixed y, fixed y1, fixed *p_y_new |
| /* Do the computation in single precision */ |
| /* if the values are small enough. */ |
| y_new = |
| - ((dy | dx_old) < 1L << (size_of(fixed) * 4 - 1) ? |
| + (((ufixed)(dy | dx_old)) < (1L << (size_of(fixed) * 4 - 1)) ? |
| dy * dx_old / dx_den : |
| (INCR_EXPR(mq_cross), fixed_mult_quo(dy, dx_old, dx_den))) |
| + y; |
| -- |
| 2.10.2 |
| |