[Xcb] update to libxcb 1.12 breaks 32bit applications

Uli Schlachter psychon at znc.in
Sun Jun 5 13:00:25 UTC 2016


Am 05.06.2016 um 13:05 schrieb G. Schlisio:
>> Please recompile libxcb with debug symbols enabled so that the
>> stack trace says more than just ??.
> done so (hopefully) and uploaded a trace here [0].
> gdb output while running was:
> Program received signal SIGSEGV, Segmentation fault.
> 0xf50ed6d1 in remove_finished_readers (completed=<optimized out>,
> prev_reader=0x980d0c8) at xcb_in.c:107
> 107         while(*prev_reader &&
> XCB_SEQUENCE_COMPARE((*prev_reader)->request, <=, completed))
> [0] http://pastebin.com/LSQktdui

Weird. I have no idea. The gdb output says "prev_reader=0x980d0c8", so this
can't be where the NULL pointer comes from. *prev_reader can't be the problem
either, because this value is checked.

Does strace still report that this crashes with a NULL pointer dereference? This
seems to be impossible, given that GDB says it is not a NULL pointer.

Also, looking through the changes since 1.11.1, I don't even see a commit that
touches this part of the code. Weird.

Sorry & cheers,
Bitte nicht mit dem verbleibenden Auge in den Laser gucken.
 - Vincent Ebert

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