It's noted in the patch that one would have to recompile linked libraries, which seems impractical, unless a distro decides to build everything with this flag.
Not just linked binaries, also the whole underlying OS, and, critically, the compiler itself. Otherwise you could replace the 'proofed' construct with one that is not proofed against the bug.
Ah right, of course. Sorry, in the midst of doing a pile of stuff I should not be commenting on this without studying it further, I figured that the first level read access would allow you to dig up the secrets required to give you write access which would then allow you the free run of the whole system, but if you are still on the other side of a virtual machine then that won't do any good unless that virtual machine can be escaped as well.
