path is rect track corners
This was triggered by an exploit that started the first
edge well outside the final rectangle, causing the captured
to exceed the correct result.
Ivan observes that we really only want the first and third
corners to compute the bounds, so remove the tracking code
that looks for a valid range of points, and record the
corners instead.
R=robertphillips@google.com
Bug: 824145,skia:7792
Change-Id: If228573d0f05c7158dba8142c144d13834e691ec
Reviewed-on: https://skia-review.googlesource.com/122081
Commit-Queue: Cary Clark <caryclark@skia.org>
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Auto-Submit: Cary Clark <caryclark@skia.org>
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 0bfeae1..0683c17 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -454,16 +454,15 @@
SkPoint lineStart; // used to construct line from previous point
const SkPoint* firstPt = nullptr; // first point in the rect (last of first moves)
const SkPoint* lastPt = nullptr; // last point in the rect (last of lines or first if closed)
- const SkPoint* lastCountedPt = nullptr; // point creating 3rd corner
+ SkPoint firstCorner;
+ SkPoint thirdCorner;
const SkPoint* pts = *ptsPtr;
const SkPoint* savePts = nullptr; // used to allow caller to iterate through a pair of rects
lineStart.set(0, 0);
- signed char directions[] = {-1, -1, -1, -1}; // -1 to 3; -1 is uninitialized
+ signed char directions[] = {-1, -1, -1, -1, -1}; // -1 to 3; -1 is uninitialized
bool closedOrMoved = false;
- bool addedLine = false;
bool autoClose = false;
bool insertClose = false;
- bool accumulatingRect = false;
int verbCnt = fPathRef->countVerbs();
while (*currVerb < verbCnt && (!allowPartial || !autoClose)) {
uint8_t verb = insertClose ? (uint8_t) kClose_Verb : fPathRef->atVerb(*currVerb);
@@ -472,11 +471,7 @@
savePts = pts;
autoClose = true;
insertClose = false;
- accumulatingRect = false;
case kLine_Verb: {
- if (accumulatingRect) {
- lastCountedPt = pts;
- }
if (kClose_Verb != verb) {
lastPt = pts;
}
@@ -488,13 +483,12 @@
if (lineStart == lineEnd) {
break; // single point on side OK
}
- addedLine = true;
int nextDirection = rect_make_dir(lineDelta.fX, lineDelta.fY); // 0 to 3
if (0 == corners) {
directions[0] = nextDirection;
- lineStart = lineEnd;
corners = 1;
closedOrMoved = false;
+ lineStart = lineEnd;
break;
}
if (closedOrMoved) {
@@ -504,28 +498,34 @@
break; // colinear with first
}
closedOrMoved = autoClose;
- lineStart = lineEnd;
if (directions[corners - 1] == nextDirection) {
if (3 == corners && kLine_Verb == verb) {
- lastCountedPt = lastPt;
+ thirdCorner = lineEnd;
}
+ lineStart = lineEnd;
break; // colinear segment
}
- if (corners >= 4) {
- return false; // too many direction changes
- }
directions[corners++] = nextDirection;
// opposite lines must point in opposite directions; xoring them should equal 2
- if (3 == corners) {
- if ((directions[0] ^ directions[2]) != 2) {
- return false;
- }
- accumulatingRect = false;
- } else if (4 == corners) {
- if ((directions[1] ^ directions[3]) != 2) {
- return false;
- }
+ switch (corners) {
+ case 2:
+ firstCorner = lineStart;
+ break;
+ case 3:
+ if ((directions[0] ^ directions[2]) != 2) {
+ return false;
+ }
+ thirdCorner = lineEnd;
+ break;
+ case 4:
+ if ((directions[1] ^ directions[3]) != 2) {
+ return false;
+ }
+ break;
+ default:
+ return false; // too many direction changes
}
+ lineStart = lineEnd;
break;
}
case kQuad_Verb:
@@ -538,15 +538,13 @@
*currVerb -= 1; // try move again afterwards
goto addMissingClose;
}
- if (!addedLine) {
+ if (!corners) {
firstPt = pts;
- accumulatingRect = true;
} else {
closeXY = *firstPt - *lastPt;
if (closeXY.fX && closeXY.fY) {
return false; // we're diagonal, abort
}
- accumulatingRect = false;
}
lineStart = *pts++;
closedOrMoved = true;
@@ -563,40 +561,24 @@
if (corners < 3 || corners > 4) {
return false;
}
- closeXY = *firstPt - *lastPt;
- // If autoClose, check if close generates diagonal
- bool result = 4 == corners && (closeXY.isZero() || (autoClose && (!closeXY.fX || !closeXY.fY)));
- if (!result) {
- if (closeXY.fX && closeXY.fY) {
- return false; // we're diagonal, abort
- }
- // check if we are just an incomplete rectangle, in which case we can
- // return true, but not claim to be closed.
- // e.g.
- // 3 sided rectangle
- // 4 sided but the last edge is not long enough to reach the start
- //
- int closeDirection = rect_make_dir(closeXY.fX, closeXY.fY);
- // make sure the close-segment doesn't double-back on itself
- if (3 == corners || 2 == (closeDirection ^ directions[1])) {
- result = true;
- autoClose = false; // we are not closed
- }
- }
if (savePts) {
*ptsPtr = savePts;
}
- if (result && rect) {
- ptrdiff_t count = lastCountedPt - firstPt + 1;
- rect->set(firstPt, (int) count);
+ // check if close generates diagonal
+ closeXY = *firstPt - *lastPt;
+ if (closeXY.fX && closeXY.fY) {
+ return false;
}
- if (result && isClosed) {
+ if (rect) {
+ rect->set(firstCorner, thirdCorner);
+ }
+ if (isClosed) {
*isClosed = autoClose;
}
- if (result && direction) {
+ if (direction) {
*direction = directions[0] == ((directions[1] + 1) & 3) ? kCW_Direction : kCCW_Direction;
}
- return result;
+ return true;
}
bool SkPath::isRect(SkRect* rect, bool* isClosed, Direction* direction) const {