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Commit f311e198 authored by henry.uh_chen's avatar henry.uh_chen Committed by Steve Kondik
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[HWUI] Infinite recursion in PathTessellator::recursiveQuadraticBezierVertices() 

Symptom: In some cases like the distance between the calculating point is very
         small, the recursion may not terminate.
         If the calculated dx and dy are 0, d is 0 too. Then the termination
         condition(d*d < TH*TH*(dx*dx*sq + dy*dy*sq)) will never be met.
         Infinite recursion will cause stack-overflow.

Solution: We added one more threshold to terminate the recursion when d is very
          small (possibly 0).

Change-Id: I7d27a72811109766766f8f8cc5d8d88e75db7f60
parent 445bac11

libs/hwui/PathTessellator.cpp

100644 → 100755
+6 −1
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ namespace android { 
namespace uirenderer {



#define THRESHOLD 0.5f

#define THRESHOLD_MIN 0.0005f

#define ROUND_CAP_THRESH 0.25f

#define PI 3.1415926535897932f
@@ -1004,7 +1005,11 @@ void PathTessellator::recursiveQuadraticBezierVertices( 
    float dy = by - ay;

    float d = (cx - bx) * dy - (cy - by) * dx;



    if (d * d < THRESHOLD * THRESHOLD * (dx * dx * sqrInvScaleY + dy * dy * sqrInvScaleX)) {

    // In some cases like the distance between the calculating point is very small, the recursion may not terminate.

    // If the calculated dx and dy are 0, d is 0 too. Then the termination condition(d*d < TH*TH*(dx*dx*sq + dy*dy*sq))

    // will never be met. Infinite recursion will cause stack-overflow.

    // We added one more threshold to terminate the recursion when d is very small (possibly 0).

    if (d * d < THRESHOLD * THRESHOLD * (dx * dx * sqrInvScaleY + dy * dy * sqrInvScaleX) || d < THRESHOLD_MIN) {

        // below thresh, draw line by adding endpoint

        pushToVector(outputVertices, bx, by);

    } else {