Date: Wed, 18 Jan 2017 10:48:58 +0000 From: Mark Rutland <mark.rutland@....com> To: PaX Team <pageexec@...email.hu> Cc: kernel-hardening@...ts.openwall.com, Kees Cook <keescook@...omium.org>, Emese Revfy <re.emese@...il.com>, "AKASHI, Takahiro" <takahiro.akashi@...aro.org>, park jinbum <jinb.park7@...il.com>, Daniel Micay <danielmicay@...il.com>, linux-kernel@...r.kernel.org, spender@...ecurity.net Subject: Re: [PATCH] gcc-plugins: Add structleak for more stack initialization On Tue, Jan 17, 2017 at 07:54:38PM +0100, PaX Team wrote: > On 17 Jan 2017 at 17:48, Mark Rutland wrote: > > That being the case, (and given the relevant bug has now been fixed), > > it's not clear to me what the value of this is today. i.e. given the > > general case, is this preventing many leaks? > > no idea, i stopped looking at the instrumentation log long ago, but everyone > can enable the debug output (has a very specific comment on it ;) and look at > the results. i keep this plugin around because it costs nothing to maintain > it and the alternative (better) solution doesn't exist yet. Fair enough; understood. > > > i never went into that direction because i think the security goal can > > > be achieved without the performance impact of forced initialization. > > > > Was there a particular technique you had in mind? > > sure, i mentioned it in my SSTIC'12 keynote (page 36): > https://pax.grsecurity.net/docs/PaXTeam-SSTIC12-keynote-20-years-of-PaX.pdf Thanks for the pointer. I'm probably being very naive here, but IIUC the per-task usercopy stack would require roughly the same analysis to identify relevant variables, unless all local variables (regardless of initialisation) that fed into a usercopy would be on the usercopy stack? Regardless, I can see the benefit of cleanly separating that data from the rest of the kernel data. Thanks, Mark.
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