drag and drop partially initiated, then hung and crashed




16 years ago
13 years ago


(Reporter: baj, Assigned: bugzilla)



Firefox Tracking Flags

(Not tracked)




16 years ago
User-Agent:       Mozilla/5.0 (X11; U; SunOS i86pc; en-US; rv:1.3) Gecko/20030325
Build Identifier: Mozilla/5.0 (X11; U; SunOS i86pc; en-US; rv:1.3) Gecko/20030325

I have a two-button "mouse" on my laptop, which simulates a third button by
clicking both buttons "at once".  Occasionally I'll fail to click both at the
exact same time, with various effects.  This evening, I found one which was
completely reproducible, and had effects varying from incomplete drag-n-drop,
to a hung browser, to a crash.

To reproduce, I click the left mouse button on a link, then click the right one
very quickly thereafter (less than .1 seconds on my 600 MHz laptop), and start
moving the mouse right after that.  I reproduced it on my housemate's laptop,
which is running the same build of Mozilla but is much faster (2.2 GHz); it
took a little more patience to reproduce, but both he and I can reproduce it.
This originally happened on a link in an eBay page, but we subsequently
reproduced it on one of the links on Google's home page.

When it successfully reproduces, the "floating page" part of the drag-n-drop
icon will be hovering somewhere near the link (which will be highlighted),
and the cursor will change to the corner-with-crosshairs drag-n-drop cursor.
No amount of clicking seems to cause it to exit this state.  (Apparently
pressing "esc" will cause it to give up, but that key is physically broken
on my laptop.)  If I switch virtual screens, it figures out that it's in a
bad state, and reverts back to normal after a few seconds.

Occasionally, rather than wedging like this, it will just crash.  I grabbed it
while it was in the process of doing so, with the following commands:

    $ truss -t'' -S segv,bus -p `pgrep mozilla-bin`
    <reproduce the problem>
    $ gcore `pgrep mozilla-bin`

I've saved the resulting core file at http://foo.net/~blakej/mozcore.gz.

A quick glance at the core file shows the following suspicious entries at the
top of the stack trace:

dd6e7003 gtk_drag_remove_icon+0x13 (0)
dd6e6255 gtk_drag_set_icon_window+0x35 (0, 0x8dfe378, -2, -2, 1)
dd6e63c4 gtk_drag_set_icon_pixmap+0xc4 (0, 0x814af00, 0x8e81c70, 0x8e81c30, -2, -2)

Notably, gtk_drag_remove_icon (and gtk_drag_set_icon_window, and
gtk_drag_set_icon_pixmap) are all called with a NULL first argument.  I don't
have the source available, but looking at the disassembly for this function,
it looks like it's really not expecting that argument to be NULL.

Reproducible: Always

Steps to Reproduce:
See "Details".
Actual Results:  
See "Details".

Expected Results:  
Not crash, and not get into a state where the cursor can't be cleared by a
single click or two.

See "Details" for a link to a core file generated at the moment of the SEGV.

Comment 1

16 years ago
I was able to reproduce the wedge on Solaris/SPARC.  Possibly a dup of
bug #147838 ?

Comment 2

16 years ago
Could be, but note that this one occasionally caused my browser to crash.
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Last Resolved: 13 years ago
Resolution: --- → EXPIRED
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