[Webkit-unassigned] [Bug 70647] New: Unreproducible crash under [ScrollbarPartAnimation setCurrentProgress:]

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=70647

           Summary: Unreproducible crash under [ScrollbarPartAnimation
                    setCurrentProgress:]
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Unspecified
        OS/Version: Unspecified
            Status: NEW
          Keywords: InRadar
          Severity: Normal
          Priority: P2
         Component: Layout and Rendering
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: bdakin at apple.com


There have been number of occurrences of a crash while animating scrollbars, though no one has been able to find reproducible steps or catch it in the debugger. The stack trace is pasted below. It appears that the FrameView has been destroyed. There is already code in place that cancels all scrollbar animations when FrameViews are destroyed, so somehow that code must be circumvented in these rare occurrences of the crash.

<rdar://problem/9542018>

0   ???                               0000000000 0 + 0
1   com.apple.WebCore                 0x993fcdbb non-virtual thunk to WebCore::FrameView::invalidateScrollbarRect(WebCore::Scrollbar*, WebCore::IntRect const&) + 107
2   com.apple.WebCore                 0x98d60102 WebCore::Scrollbar::invalidateRect(WebCore::IntRect const&) + 44
3   com.apple.WebCore                 0x9952e1f9 -[ScrollbarPartAnimation setCurrentProgress:] + 265
4   com.apple.AppKit                  0x95f3fc8c -[NSAnimation(NSInternal) _advanceTimeWithTimer:] + 409
5   com.apple.Foundation              0x973dc373 __NSFireTimer + 166
6   com.apple.CoreFoundation          0x976ee256 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 22
7   com.apple.CoreFoundation          0x976edbe7 __CFRunLoopDoTimer + 743
8   com.apple.CoreFoundation          0x976ccce0 __CFRunLoopRun + 1888
9   com.apple.CoreFoundation          0x976cc1ec CFRunLoopRunSpecific + 332
10  com.apple.CoreFoundation          0x976cc098 CFRunLoopRunInMode + 120
11  com.apple.HIToolbox               0x90007487 RunCurrentEventLoopInMode + 318
12  com.apple.HIToolbox               0x9000edc3 ReceiveNextEventCommon + 381
13  com.apple.HIToolbox               0x9000ec32 BlockUntilNextEventMatchingListInMode + 88
14  com.apple.AppKit                  0x95d648ec _DPSNextEvent + 678
15  com.apple.AppKit                  0x95d64159 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 113
16  com.apple.AppKit                  0x95d604cb -[NSApplication run] + 904
17  com.apple.WebKit2                 0x97cdf198 RunLoop::run() + 56
18  com.apple.WebKit2                 0x97d063b0 WebKit::WebProcessMain(WebKit::CommandLine const&) + 628
19  com.apple.WebKit2                 0x97cf1629 WebKitMain + 309
20  com.apple.WebProcess              0x00035dfd 0x35000 + 3581

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