Pidgin remote crash from long URLs

Mark Doliner mark at
Sun Mar 3 22:36:11 EST 2013

A guy on our support list mentioned[1][2] that his Pidgin crashes if
someone sends him a long URL.  I can reproduce this by pasting a long
URL[3] in the text input box in 2.x.y (I haven't tested 3.0.0).  My
best guess is that an x library function can't allocate a huge amount
of memory and exits the entire process.

1. "gdb pidgin"

2. "break gdk_x_error"
You'll probably need to type "y" to make breakpoint pending on future
shared library load.  Or you could run first then add the breakpoint.

3. "run --sync"
--sync probably isn't actually necessary.  Theoretically it should
make the backtrace more useful.  Like, maybe it could actually show
the Pidgin calls that trigger the problem?  Or maybe the problem call
starts from the gtk main loop, so there would never be Pidgin code in
the backtrace.  It's also possible we don't pass our args to the right
places to make --sync work.

4. "cont"
I hit this breakpoint when Pidgin starts for some reason.  I've just
been continuing.  Doesn't seem to affect anything.

5. Open an IM window.

6. Paste the long URL from footnote #3.

7. Mouse over the long URL.

8. Hit the breakpoint and run "bt"

#0  gdk_x_error (display=0x740e30, error=0x7fffffffbc20)
    at /build/buildd/gtk+2.0-2.24.13/gdk/x11/gdkmain-x11.c:458
#1  0x00007ffff73b94f6 in _XError () from /usr/lib/x86_64-linux-gnu/
#2  0x00007ffff73b6741 in ?? () from /usr/lib/x86_64-linux-gnu/
#3  0x00007ffff73b6785 in ?? () from /usr/lib/x86_64-linux-gnu/
#4  0x00007ffff73b7378 in _XReply () from /usr/lib/x86_64-linux-gnu/
#5  0x00007ffff73b2d3d in XSync () from /usr/lib/x86_64-linux-gnu/
#6  0x00007ffff73b2dcb in ?? () from /usr/lib/x86_64-linux-gnu/
#7  0x00007ffff73b9e2f in ?? () from /usr/lib/x86_64-linux-gnu/
#8  0x00007ffff7395d14 in XCreatePixmap () from
#9  0x00007ffff62bd0d2 in _gdk_pixmap_new (drawable=0x186ec60,
width=width at entry=32774, height=25, depth=24,
    depth at entry=-1) at /build/buildd/gtk+2.0-2.24.13/gdk/x11/gdkpixmap-x11.c:175
#10 0x00007ffff6289617 in IA__gdk_pixmap_new
(drawable=drawable at entry=0x186ec60, width=width at entry=32774,
    height=<optimized out>, depth=depth at entry=-1) at
#11 0x00007ffff6297036 in gdk_window_begin_implicit_paint
(rect=0x7fffffffbed0, window=0x186ec60)
    at /build/buildd/gtk+2.0-2.24.13/gdk/gdkwindow.c:2779
#12 gdk_window_process_updates_internal (window=0x186ec60) at
#13 0x00007ffff6299201 in IA__gdk_window_process_all_updates ()
    at /build/buildd/gtk+2.0-2.24.13/gdk/gdkwindow.c:5696
#14 0x00007ffff6299269 in gdk_window_update_idle (data=<optimized out>)
    at /build/buildd/gtk+2.0-2.24.13/gdk/gdkwindow.c:5322
#15 0x00007ffff6276e77 in gdk_threads_dispatch (data=0x1a45c40) at
#16 0x00007ffff53d8ab5 in g_main_context_dispatch () from
#17 0x00007ffff53d8de8 in ?? () from /lib/x86_64-linux-gnu/
#18 0x00007ffff53d91e2 in g_main_loop_run () from
#19 0x00007ffff663ec77 in IA__gtk_main () at
#20 0x0000000000499950 in main (argc=1, argv=0x7fffffffe538) at gtkmain.c:933

The program 'Pidgin' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadAlloc (insufficient resources for operation)'.
  (Details: serial 14454 error_code 11 request_code 53 minor_code 0)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

I think it's kinda lame that gdk/gtk/xlib/whatever barfs when we give
it a ridiculously wide pango layout, but whatever.  I'm assuming this
problem is gtkimhtml specific, and so I don't want to spend a whole
lot of time fixing it.  As an easy fix I want to just truncate the URL
displayed in the tooltip to 200 characters.  See attached patch.

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