X.Org X Server stack overflow and information leak

[Marcus Meissner <meissner () suse de>]

Hi,

This issue got lost under the Qualys noise :(

https://bugzilla.suse.com/show_bug.cgi?id=1035283

CVE-2017-10971:
        The endianess handling for X Events assumed a fixed size of X Event structures and
        had a specific 32 byte stack buffer for that. 

        However "GenericEvents" can have any size, so if the events were sent in the wrong
        endianess, this stack buffer could be overflowed easily.

        So authenticated X users could overflow the stack in the X Server and with the X 
        server usually running as root gaining root prileveges.

        https://cgit.freedesktop.org/xorg/xserver/commit/?id=ba336b24052122b136486961c82deac76bbde455
        https://cgit.freedesktop.org/xorg/xserver/commit/?id=8caed4df36b1f802b4992edcfd282cbeeec35d9d
        https://cgit.freedesktop.org/xorg/xserver/commit/?id=215f894965df5fb0bb45b107d84524e700d2073c


CVE-2017-10972:
        https://cgit.freedesktop.org/xorg/xserver/commit/?id=05442de962d3dc624f79fc1a00eca3ffc5489ced

        An information leak out of the X server due to an uninitialized stack area when swapping
        event endianess.

Ciao, Marcus