linux-kernel - Re: pt_regs leak into userspace (was Re: [PATCH v3 20/71] ARC: Signal handling)

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Date:	Mon, 11 Feb 2013 11:01:47 +0000
From:	James Hogan <james.hogan@...tec.com>
To:	Jonas Bonn <jonas.bonn@...il.com>
CC:	Vineet Gupta <Vineet.Gupta1@...opsys.com>,
	Arnd Bergmann <arnd@...db.de>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: pt_regs leak into userspace (was Re: [PATCH v3 20/71] ARC: Signal
 handling)

Hi Jonas,

On 11/02/13 10:53, Jonas Bonn wrote:
> And now that I think about it some more, I think this is done
> incorrectly in the openrisc arch, too, as the fast-path for
> rt_sigreturn probably only restores the call-clobbered regs.
> sigreturn probably needs to be special-cased to _always_ restore all
> the regs on its way back to userspace.  Not for the "signal" case, but
> for the "setcontext" case; but these two are pretty-much
> indistinguishable.

Wouldn't setcontext restore a different stack, so the sigreturn wouldn't
happen until the ucontext is switched back?

Cheers
James

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