Closed Bug 645289 Opened 9 years ago Closed 9 years ago
Crash [@ ns
NPAPIPlugin Instance::Get Image ] mainly with Webex
It is a new crash signature that first appeared in 4.0b12. It is #7 top crasher on Mac OS X in 4.0. Most comments talk about Webex. Signature nsNPAPIPluginInstance::GetImage UUID cad2d71a-1982-494b-b7a6-5d4f22110324 Time 2011-03-24 21:48:04.45510 Uptime 91254 Last Crash 9751821 seconds (more than 3 months) before submission Install Age 450096 seconds (5.2 days) since version was first installed. Product Firefox Version 4.0 Build ID 20110318052756 Branch 2.0 OS Mac OS X OS Version 10.5.8 9L31a CPU x86 CPU Info family 6 model 23 stepping 6 Crash Reason EXC_BAD_ACCESS / KERN_INVALID_ADDRESS Crash Address 0x6800003d User Comments www.xbox.com App Notes Renderers: 0x22600,0x20400 Frame Module Signature [Expand] Source 0 XUL nsNPAPIPluginInstance::GetImage modules/plugin/base/src/nsNPAPIPluginInstance.cpp:882 1 XUL nsPluginInstanceOwner::SetCurrentImage layout/generic/nsObjectFrame.cpp:2000 2 XUL nsPluginInstanceOwner::InvalidateRect layout/generic/nsObjectFrame.cpp:3499 3 XUL nsNPAPIPluginInstance::InvalidateRect modules/plugin/base/src/nsNPAPIPluginInstance.cpp:1215 4 XUL mozilla::plugins::parent::_invalidaterect modules/plugin/base/src/nsNPAPIPlugin.cpp:1268 5 agcore agcore@0x898e1b 6 agcore agcore@0x6520d8 7 agcore agcore@0x6632eb 8 agcore agcore@0x663f56 9 agcore agcore@0x664148 10 CoreFoundation __CFRunLoopDoObservers 11 CoreFoundation CFRunLoopRunSpecific 12 CoreFoundation CFRunLoopRunInMode 13 Foundation -[NSRunLoop runMode:beforeDate:] 14 XUL nsAppShell::ProcessNextNativeEvent widget/src/cocoa/nsAppShell.mm:664 15 XUL nsBaseAppShell::OnProcessNextEvent widget/src/xpwidgets/nsBaseAppShell.cpp:173 16 XUL nsAppShell::OnProcessNextEvent widget/src/cocoa/nsAppShell.mm:833 17 XUL nsThread::ProcessNextEvent xpcom/threads/nsThread.cpp:597 18 XUL NS_ProcessPendingEvents_P nsThreadUtils.cpp:200 19 XUL nsBaseAppShell::NativeEventCallback widget/src/xpwidgets/nsBaseAppShell.cpp:132 20 XUL nsAppShell::ProcessGeckoEvents widget/src/cocoa/nsAppShell.mm:399 21 CoreFoundation CFRunLoopRunSpecific 22 CoreFoundation CFRunLoopRunInMode 23 HIToolbox RunCurrentEventLoopInMode 24 HIToolbox ReceiveNextEventCommon 25 HIToolbox BlockUntilNextEventMatchingListInMode 26 AppKit _DPSNextEvent 27 AppKit -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] 28 AppKit -[NSApplication run] 29 XUL nsAppShell::Run widget/src/cocoa/nsAppShell.mm:746 30 XUL nsAppStartup::Run toolkit/components/startup/src/nsAppStartup.cpp:220 31 XUL XRE_main toolkit/xre/nsAppRunner.cpp:3786 32 firefox-bin main browser/app/nsBrowserApp.cpp:158 33 firefox-bin firefox-bin@0xa05 34 @0x1 More reports at: https://crash-stats.mozilla.com/report/list?range_value=4&range_unit=weeks&signature=nsNPAPIPluginInstance%3A%3AGetImage
I've been debugging bug 633452, I'm pretty sure this is the same crash. The stack is different every once in a while but the underlying problem is the same. I can reproduce bug 633452 reliably and every once in a while I get this stack.
The problem here is that we miscalculate whether or not a plugin has running instances. "nsPluginHost::IsRunningPlugin" is only asking the first instance for any given MIME type if it is running. In the case where the first instance isn't running but a second instance is, "IsRunningPlugin" will incorrectly claim that there is no running instance. That can lead to us deleting the nsNPAPIPlugin object from under a running instance, bad times. This crash shows up the second time you try to load a WebEx meeting because it's the second time we try to load an instance for the MIME type "x-java-vm". The first instance is no longer running but the second one is. Then the page refreshes the plugin list to look for a newly installed WebEx plugin (which would have been installed by the Java instance), and refreshing the plugin list attempts to delete nsNPAPIPlugin objects that don't have running instances. The nsNPAPIPlugin object gets incorrectly deleted from under the running Java instance and we crash. I'm putting this patch on this bug because I saw this stack most often while debugging, however I'm pretty sure this will also fix bug 633452. Same underlying problem.
Attachment #522606 - Flags: review?(benjamin)
Marking this as security sensitive in case this is exploitable. Seems like that might be possible since content can trigger access to a deleted nsNPAPIPlugin object. We can open this up again if others think this isn't an issue but I want to play it safe.
To be a little more clear about the way in which the object gets incorrectly deleted... "nsPluginHost::ReloadPlugins" calls "IsRunningPlugin" to determine whether it can call "TryUnloadPlugin" on the plugin's nsPluginTag object. "nsPluginTag::TryUnloadPlugin" will null out its entry point, an nsNPAPIPlugin object, which releases it and often destroys it. This crash happens when "IsRunningPlugin" incorrectly claims there is no running instance for the plugin and "TryUnloadPlugin" ends up destroying the nsNPAPIPlugin object out from underneath a running instance. At some later point the running instance tries to call a method on the deleted object, in this case during an invalidation.
pushed to mozilla-central http://hg.mozilla.org/mozilla-central/rev/1b56b31b790f
Status: NEW → RESOLVED
Closed: 9 years ago
Resolution: --- → FIXED
We should take this for Firefox 4. I've been working on a minimal test case but so far I haven't been able to figure out exactly what the web page is doing to get the first instance that is no longer running to remain in the plugin instances array.
I looked at the 1.9.2 code and while the bug that caused this problem exists there (miscalculating the number of live plugin instances for a plugin), the pointer to the deleted object that is causing the specific dangerous crash here does not exist. At least not in the same place. The live instance calculation bug could cause all sorts of hard-to-guess trouble as a result of premature deletion (among other things), I think we should fix it on 1.9.2.
Comment on attachment 522606 [details] [diff] [review] fix v1.0 Approved for mozilla2.0 repository, a=dveditz for release-drivers
Attachment #522606 - Flags: approval2.0+
Comment on attachment 522823 [details] [diff] [review] fix v1.0 for 1.9.2 Approved for 22.214.171.124, a=dveditz for release-drivers Please land ASAP so we get this into 3.6.17 which will release around the same time as 4.0.1
Attachment #522823 - Flags: approval126.96.36.199? → approval188.8.131.52+
pushed to mozilla-1.9.2 http://hg.mozilla.org/releases/mozilla-1.9.2/rev/57f12d60226f
pushed to mozilla-2.0 http://hg.mozilla.org/releases/mozilla-2.0/rev/62e68e402bfd
Whiteboard: [sg:critical?] → [sg:critical?] (no crash in 3.6.x)
Crash Signature: [@ nsNPAPIPluginInstance::GetImage ]
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