Bug 32489

Summary: feMerge crahses if feMergeNodes attribute in is empty
Product: WebKit Reporter: Dirk Schulze <krit>
Component: SVGAssignee: Nobody <webkit-unassigned>
Severity: Normal CC: commit-queue, webkit.review.bot, zimmermann
Priority: P2    
Version: 525.x (Safari 3.1)   
Hardware: PC   
OS: OS X 10.5   
Bug Depends on:    
Bug Blocks: 68469, 26389    
Description Flags
feMergeNode empty -- crash
fix of feMerge none

Description Dirk Schulze 2009-12-13 08:43:43 PST
Created attachment 44757 [details]
feMergeNode empty -- crash

If one of the feMergeNodes attribute 'in' is empty and the related feMerge element is not the first effect of the filter, webkit crashes.

If the 'in' attribute is empty, SVGFilterBuilder::getElementById gives either one of the predefined SourceGraphics back or the last effect that was added.
This works if there is no last effect. The SourceGraphic is given back and no crash appears. We have a test for this: svg/custom/emty-merge.svg.

In the case of a lastEffect, getElementId also gives the right effect back. But WebKit crashes during WebCore::FilterEffect::calculateEffectRect in FEMerge. I don't have a debug build atm, but I guess that the reference to the last effect is bogus.

I attached an example. Everything works, if feOffset gets an result="" and the mergeNode adresses this result.
Comment 1 Dirk Schulze 2009-12-16 13:24:30 PST
Created attachment 45010 [details]
fix of feMerge

Take the reference of the effect not just the pointer. This fixes the crash.
Comment 2 Dirk Schulze 2009-12-16 13:25:03 PST
Comment on attachment 45010 [details]
fix of feMerge

sorry, wrong flag.
Comment 3 WebKit Review Bot 2009-12-16 13:29:33 PST
style-queue ran check-webkit-style on attachment 45010 [details] without any errors.
Comment 4 Nikolas Zimmermann 2009-12-16 13:45:41 PST
Comment on attachment 45010 [details]
fix of feMerge

LGTM, r=me.
Comment 5 WebKit Commit Bot 2009-12-16 13:57:02 PST
Comment on attachment 45010 [details]
fix of feMerge

Clearing flags on attachment: 45010

Committed r52219: <http://trac.webkit.org/changeset/52219>
Comment 6 WebKit Commit Bot 2009-12-16 13:57:06 PST
All reviewed patches have been landed.  Closing bug.