51096 - Changing the mousewheel settings twice, then using the wheel, crashes the browser

Status: VERIFIED FIXED

(Core :: XUL, defect, P3)

Description

[Jan Carpenter]

Overview Description: 
On Windows platforms only, entering prefs and changing the mousewheel setting, 
exiting, and then doing it again, will cause the browser to crash the next time 
you use the mousewheel.

Steps to Reproduce: 
- Edit prefs
- Under Advanced/Mousewheel change the setting to any other setting
- Save/exit prefs (mousewheel works fine)
- Repeat above, and change mousewheel setting to something else
- Save/exit prefs and use mousewheel

Actual Results: 
Browser crashes

Build Date & Platform Bug Found: 
2000-09-01-11-M18 : Win32

Additional Builds and Platforms Tested On: 
2000-09-01-10-M18 : Linux (worked fine, no crash)

Additional Information:
Attaching Talkback report: 16705902

Comment 1

[Jan Carpenter]

Attachment: Talkback report

Comment 2

[Jan Carpenter]

adding crash keyword

Comment 3

[Peter Trudelle]

reassigning to bryner, nominating for nsbeta3.  How likely is this scenario?
How critical are these prefs?  

Comment 4

[Brian Ryner (not reading)]

Here is the relevant section of code from that build:

 781 bryner    1.188   nsCOMPtr<nsIScriptGlobalObject> ourGlobal;
 782                  
gLastFocusedDocument->GetScriptGlobalObject(getter_AddRefs(ourGlobal));
 783 vidur     1.199   nsCOMPtr<nsIDOMWindowInternal> rootWindow;
 784 bryner    1.188   nsCOMPtr<nsPIDOMWindow> ourWindow =
do_QueryInterface(ourGlobal);
 785                   NS_ENSURE_TRUE(ourWindow, NS_ERROR_FAILURE);

It looks to me like the crash at line 784 could really only happen if
'ourGlobal' was garbage.  cc'ing saari to see if he knows how this could happen. 

Comment 5

[Peter Trudelle]

saari is on vacation this week. Do we need to interrupt him for this?

Comment 6

[Brian Ryner (not reading)]

No, I don't think so.

One obvious thing I could try is simply a null check on ourGlobal.  I'm not sure
this would fix the problem but it certainly wouldn't hurt.  Should I go ahead
and check that in?

Comment 7

[Peter Trudelle]

If that will prevent the crash, and not just relocate it, then I'd take it.

Comment 8

[Peter Trudelle]

nsbeta3+/P3, just to stop the crash.

Comment 9

[Brian Ryner (not reading)]

Fix checked in.

Comment 10

[John Morrison]

Jan, can you verify this? (I am mousewheel-deprived ...)

Comment 11

[Jan Carpenter]

verified: 
2000-10-23-09-MN6 : win32