Bug 65492 – Crash in MainFrameScrollbarGtk::detachAdjustment (v. 1.4.2)

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Ed Catmur]

See downstream for full stack trace.

#0  0x005457a3 in g_type_check_instance_cast (type_instance=0xfffffffe, iface_type=80) at gtype.c:3969
#1  0x42489475 in WebCore::MainFrameScrollbarGtk::detachAdjustment (this=0xad9131b0) at WebCore/platform/gtk/MainFrameScrollbarGtk.cpp:79
#2  0x4249543b in WebCore::ScrollView::setHorizontalAdjustment (this=0xa8bc7a00, hadj=0x0, resetValues=true) at WebCore/platform/gtk/ScrollViewGtk.cpp:92
#3  0x42495705 in WebCore::ScrollView::setGtkAdjustments (this=0xa8bc7a00, hadj=0x0, vadj=0x0, resetValues=true) at WebCore/platform/gtk/ScrollViewGtk.cpp:161
#4  0x424c7ecd in WebKit::FrameLoaderClient::savePlatformDataToCachedFrame (this=0xa8ba50d0, cachedFrame=0xadd4ed20) at WebKit/gtk/WebCoreSupport/FrameLoaderClientGtk.cpp:1270
#5  0x41f1012e in WebCore::CachedFrame::CachedFrame (this=0xadd4ed20, frame=0xa8ba0c00) at WebCore/history/CachedFrame.cpp:144
#6  0x41f1017c in create (this=0xadd4e780, frame=0xaa23c200) at WebCore/history/CachedFrame.h:73
#7  WebCore::CachedFrame::CachedFrame (this=0xadd4e780, frame=0xaa23c200) at WebCore/history/CachedFrame.cpp:148
#8  0x41f10502 in create (this=0xb6fa9260, page=0xad19df20) at WebCore/history/CachedFrame.h:73

On branch releases/WebKitGTK/webkit-1.4, if a ScrollView that previously did not have a parent acquires a parent, ScrollView::setHorizontalAdjustment()/ScrollView::setVerticalAdjustment() expect m_horizontalScrollbar/m_verticalScrollbar to be a MainFrameScrollbarGtk when it is actually a Scrollbar.  Result is heap UMR or similar.

Proposed fix is to remove the scrollbars when a ScrollView that previously did not have a parent acquires a parent; patch to follow.

Trunk does not have this issue as the dangerous casts are absent.

[Ed Catmur]

Created attachment 102568 [details]
MainFrameScrollbarGtk.patch

[Martin Robinson]

Perhaps the right thing to do here is to merge the real scrollbar fix into stable. This was the one which moved adjustment handling out of WebCore entirely.

[Gustavo Noronha (kov)]

I'm in favor of what you propose Martin. It's a big change, but also one we know improves stability by making the whole thing less complex.

[Martin Robinson]

Should be fixed as of http://trac.webkit.org/changeset/94012. This fix will be in WebKitGTK+ 1.4.3.