Bug 207417 – An SVG animated property animator can stop animation while other animators are still running

• Component: SVG
• Status: RESOLVED FIXED

[Wen Xu]

A crash that can be reproduced with both master branch and Safari release.

PoC:

<svg id="v6" xmlns="http://www.w3.org/2000/svg">
<clipPath id="v54">
  <animate id="v55" attributeName="clipPathUnits"></animate>
  <set id="v57" attributeName="clipPathUnits" max="1s" min="0s" repeatCount="256" tabindex="2"></set>
  <set id="v63" attributeName="clipPathUnits"></set>
</clipPath>
</svg>

Log:
AddressSanitizer:DEADLYSIGNAL
=================================================================
==76736==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x00048898088b bp 0x7ffee5d45bd0 sp 0x7ffee5d45b20 T0)
==76736==The signal is caused by a READ memory access.
==76736==Hint: address points to the zero page.
==76736==WARNING: invalid path to external symbolizer!
==76736==WARNING: Failed to use and restart external symbolizer!
    #0 0x48898088a in void WebCore::SVGAnimatedDecoratedProperty<WebCore::SVGDecoratedEnumeration, unsigned int>::setAnimVal<WebCore::SVGUnitTypes::SVGUnitType>(WebCore::SVGUnitTypes::SVGUnitType const&) (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x4e7288a)
    #1 0x48897fd61 in WebCore::SVGAnimatedEnumerationAnimator<WebCore::SVGUnitTypes::SVGUnitType>::animate(WebCore::SVGElement*, float, unsigned int) (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x4e71d61)
    #2 0x48891b0fb in WebCore::SVGAnimateElementBase::calculateAnimatedValue(float, unsigned int) (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x4e0d0fb)
    #3 0x488957844 in WebCore::SVGAnimationElement::updateAnimation(float, unsigned int) (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x4e49844)
    #4 0x488da09b5 in WebCore::SVGSMILElement::progress(WebCore::SMILTime, WebCore::SVGSMILElement&, bool) (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x52929b5)
    #5 0x488db3405 in auto WebCore::SMILTimeContainer::updateAnimations(WebCore::SMILTime, bool)::$_2::operator()<WebCore::SVGSMILElement>(WebCore::SVGSMILElement*) const (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x52a5405)
    #6 0x488d961ca in WebCore::SMILTimeContainer::processAnimations(WTF::Vector<WebCore::SVGSMILElement*, 0ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc> const&, WTF::Function<void (WebCore::SVGSMILElement*)>&&) (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x52881ca)
    #7 0x488d949ab in WebCore::SMILTimeContainer::updateAnimations(WebCore::SMILTime, bool) (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x52869ab)
    #8 0x488d93160 in WebCore::SMILTimeContainer::timerFired() (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x5285160)
    #9 0x487c452c6 in WebCore::ThreadTimers::sharedTimerFiredInternal() (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x41372c6)
    #10 0x487cbc77e in WebCore::timerFired(__CFRunLoopTimer*, void*) (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x41ae77e)
    #11 0x7fff2f251803 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x9f803)
    #12 0x7fff2f2513bd in __CFRunLoopDoTimer (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x9f3bd)
    #13 0x7fff2f250e9d in __CFRunLoopDoTimers (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x9ee9d)
    #14 0x7fff2f235aec in __CFRunLoopRun (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x83aec)
    #15 0x7fff2f234bd2 in CFRunLoopRunSpecific (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x82bd2)
    #16 0x7fff318d81a7 in -[NSRunLoop(NSRunLoop) runMode:beforeDate:] (/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation:x86_64+0x611a7)
    #17 0x7fff3198bd8a in -[NSRunLoop(NSRunLoop) run] (/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation:x86_64+0x114d8a)
    #18 0x7fff66b290e0 in _xpc_objc_main.cold.4 (/usr/lib/system/libxpc.dylib:x86_64+0x170e0)
    #19 0x7fff66b29026 in _xpc_objc_main (/usr/lib/system/libxpc.dylib:x86_64+0x17026)
    #20 0x7fff66b28b59 in xpc_main (/usr/lib/system/libxpc.dylib:x86_64+0x16b59)
    #21 0x47898d4c5 in WebKit::XPCServiceMain(int, char const**) (/Users/test/workspace/webkit/WebKitBuild/Release/WebKit.framework/Versions/A/WebKit:x86_64+0x98d4c5)
    #22 0x7fff668da7fc in start (/usr/lib/system/libdyld.dylib:x86_64+0x1a7fc)

==76736==Register values:
rax = 0x0000100000000000  rbx = 0x00007ffee5d45b60  rcx = 0x00000000e5d45b03  rdx = 0x00001fffdcba8b04
rdi = 0x0000000000000000  rsi = 0x00007ffee5d45b40  rbp = 0x00007ffee5d45bd0  rsp = 0x00007ffee5d45b20
 r8 = 0x0000100000000000   r9 = 0x00000fffffffffff  r10 = 0x0000000000000000  r11 = 0xffffffffffffffff
r12 = 0x0000606000053028  r13 = 0x00007ffee5d45b20  r14 = 0x0000000000000000  r15 = 0x00001fffdcba8b64
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/Users/test/workspace/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x4e7288a) in void WebCore::SVGAnimatedDecoratedProperty<WebCore::SVGDecoratedEnumeration, unsigned int>::setAnimVal<WebCore::SVGUnitTypes::SVGUnitType>(WebCore::SVGUnitTypes::SVGUnitType const&)
==76736==ABORTING
2020-02-07 19:20:31.663 MiniBrowser[76735:774496] WebContent process crashed; reloading

it seems that updateAnimation is called after stopAnimation, and |m_animVal| has already become null. is this a racing?


Reported by Wen Xu from SSLab at Georgia Tech.

[Radar WebKit Bug Importer]

<rdar://problem/59278306>

[Said Abou-Hallawa]

Created attachment 390330 [details]
Patch

[Said Abou-Hallawa]

Comment on attachment 390330 [details]
Patch

Will post a cleaner patch.

[Ryosuke Niwa]

There is no security implication here.

[Said Abou-Hallawa]

Created attachment 399788 [details]
Patch

[Said Abou-Hallawa]

Created attachment 399789 [details]
Patch

[Said Abou-Hallawa]

Created attachment 400293 [details]
Patch

[EWS]

Committed r262175: <https://trac.webkit.org/changeset/262175>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 400293 [details].