Re: [PATCH] compat: Fix RT signal mask corruption via sigprocmask

[Linus Torvalds]

On Wed, May 9, 2012 at 3:09 PM, Jan Kiszka <jan.kiszka@xxxxxxxxxxx> wrote:
> compat_sys_sigprocmask reads a smaller signal mask from userspace than
> sigprogmask accepts for setting. So the high word of blocked.sig[0] will
> be cleared, releasing any potentially blocked RT signal.

I see what you're trying to do, but I think your patch is wrong.

It may work for SIG_BLOCK and SIG_SETMASK to use the current blocked
bits in the high bits, but I'm pretty sure it doesn't work at all for
SIG_UNBLOCK.

I suspect that compat_sys_sigprocmask() should simply be rewritten to
*not* use sys_sigprocmask() at all, but simply open-code the three
cases directly. IOW, copy the code from sys_sigprocmask(), and modify
it for an incoming/outgoing compat_old_sigset_t.

Hmm?

                    Linus
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