> | enough space on the stack to fit a complete siginfo_t and then only copy out
> | the currently used part (i.e. struct _ksiginfo).  This would also fix the
> | problem that right now we leak unused kernel memory to userspace, because we
> | don't clear the padding part of siginfo_t (Yamamoto Takashi mentioned this
> | to me in private email).
> 
> BTW, this is the case [leaking kernel memory info] in many of the siginfo
> machdep.c files (sparc,sparc64,vax, etc.) It did not seem important at
> the time, but maybe we should bring it up for discussion again.

Hmm, we discussed this before..

There's no kernel leak. But there is `undefined' memory on the user
process's stack, where `undefined' is actually determined by whatever
the process did with its user stack before.

-pk