Please consider backporting a p11-kit deadlock fix

This package doesn't seem to be set up with an upstream tracker link. Here's the upstream bug:

https://bugs.freedesktop.org/show_bug.cgi?id=84567

We'd need the information in https://wiki.ubuntu.com/StableReleaseUpdates#SRU_Bug_Template - including a test case. Did you look at how cleanly the upstream patch applies?

Here are my attempts to answer the questions in the SRU template. I'm not an Ubuntu developer, and I don't speak Debian package language (I speak RPM, but that's rather different), so I'm not going to send an actual debdiff or whatever it's called.

Note, however, that I confused myself with the git history. The latest upstream release in the 0.20 series is 0.20.7, and 0.20.7 does not have the fix. The fix I linked applies directly on top of 0.20.7.

This bug should therefore be fixed in Vivid before worrying about backports.

The fix does *not* apply to 0.20.3 as is. I can try to backport it, but I'd want confirmation that it would be likely to be applied (as opposed to bumping p11-kit to a newer microrelease or just leaving it unfixed).

[Impact]

Multithreaded programs that use p11-kit and call fork can deadlock due to a race. More complex programs that use certain malloc replacements and link to libraries like libvmime may deadlock when forking as well, even if they don't use p11-kit.

The deadlock is caused by the use of non async-signal-safe functions in an atfork handler in p11-kit.

[Test Case]

Compile and run the attached program. With a buggy p11-kit, it is very likely to deadlock. With a fixed p11-kit, it will exit after about five seconds.

[Regression Potential]

When I looked at the patch, it looked straightforward.

Status changed to 'Confirmed' because the bug affects multiple users.