From f41da8f8e0f6f41ca522279274da1f2441828eda Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Sun, 24 Mar 2019 17:11:55 +0100
Subject: vandg inverse: avoid division by zero

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13894
Credit to OSS Fuzz
---
 src/projections/vandg.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/projections/vandg.cpp b/src/projections/vandg.cpp
index 89620356..c669f8fa 100644
--- a/src/projections/vandg.cpp
+++ b/src/projections/vandg.cpp
@@ -80,7 +80,14 @@ static PJ_LP s_inverse (PJ_XY xy, PJ *P) {           /* Spheroidal, inverse */
     al = c1 / c3 - THIRD * c2 * c2;
     m = 2. * sqrt(-THIRD * al);
     d = C2_27 * c2 * c2 * c2 + (c0 * c0 - THIRD * c2 * c1) / c3;
-    if (((t = fabs(d = 3. * d / (al * m))) - TOL) <= 1.) {
+    const double al_mul_m = al * m;
+    if( al_mul_m == 0 ) {
+        proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
+        return proj_coord_error().lp;
+    }
+    d = 3. * d /al_mul_m;
+    t = fabs(d);
+    if ((t - TOL) <= 1.) {
         d = t > 1. ? (d > 0. ? 0. : M_PI) : acos(d);
         lp.phi = M_PI * (m * cos(d * THIRD + PI4_3) - THIRD * c2);
         if (xy.y < 0.) lp.phi = -lp.phi;
-- 
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