Avoid use-after-free in _XimProtoSetIMValues()

[Matthias Dieter Wallnöfer]

I think that the patch https://gitlab.freedesktop.org/xorg/lib/libx11/commit/003e30a66a249f5c70b30d1c187385124cd4cdad (issue: https://gitlab.freedesktop.org/xorg/lib/libx11/issues/49) should be backported to both Ubuntu 16.04 LTS Xenial and Ubuntu 18.04 LTS Bionic.

Although it didn't get an explicit CVS, use-after-free scenarios should not get underestimated.

[Sebastien Bacher (seb128)]

Thank you for your bug report. That eems indeed worth fixing, it's a bit difficult to know how sensitive the problem is without details though. Could you provide a bit more context on the bug, maybe a way to trigger it?

[Matthias Dieter Wallnöfer (mwallnoefer)]

Unfortunately I just stumbled over this commit by accident since I checked the commit log of libX11. So for a reproduction we would need to contact the original reporter Sami Farin (https://bugs.freedesktop.org/show_bug.cgi?id=93186) but I do not find any valid email address from him.

[Matthias Dieter Wallnöfer (mwallnoefer)]

Any news on this?

[Timo Aaltonen (tjaalton)]

this is fixed in 1.6.8-1 in eoan

an SRU can be considered if there's a use-case which benefits from it, but sounds like there is none