diff options
| author | Robin Watts <Robin.Watts@artifex.com> | 2016-12-29 15:57:43 +0000 |
|---|---|---|
| committer | Robin Watts <Robin.Watts@artifex.com> | 2016-12-29 16:02:25 +0000 |
| commit | 4bef1a1d32e29b68855616020dbff574b9cda08f (patch) | |
| tree | eb2afd3be3993ad5e8b029a49032349c65d0f361 | |
| parent | 0aeb0bbd41cc16e70ab6e4b1d56e0c510bf2a758 (diff) | |
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
| -rw-r--r-- | base/gxfill.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/base/gxfill.c b/base/gxfill.c index 99196c087..2f81bb0b1 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; |
