From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Daniel Micay <danielmicay@gmail.com>,
Ingo Molnar <mingo@kernel.org>, Kees Cook <keescook@chromium.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Alexander Popov <alex.popov@linux.com>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
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Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>,
X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC v9 4/7] x86/entry: Erase kernel stack in syscall_trace_enter()
Date: Tue, 6 Mar 2018 11:16:51 -0800 [thread overview]
Message-ID: <CA+55aFxkzxhGaK=sp2CqM1YFEE=fL33wC1TR4KKqsRqPGto6yA@mail.gmail.com> (raw)
In-Reply-To: <CAKv+Gu_VaO39h8trgsNhU4JEVkdgoFWGoovBdmAL_YsHe7Nq1Q@mail.gmail.com>
On Tue, Mar 6, 2018 at 11:07 AM, Ard Biesheuvel
<ard.biesheuvel@linaro.org> wrote:
>
> The compiler usually does a pretty good job of detecting which scalar
> variables are never initialized by regular assignment.
Sure, but "usually" is not really the same as always. Sometimes scalar
types are initialized by passing a reference to them too.
> We could easily extend this to scalar and array types, but we'd first
> need to see what the performance impact is, because I don't think it
> will be negligible.
For scalar types, I suspect it will be entirely unnoticeable, because
they are not only small, but it's rare that this kind of "initialize
by passing a reference" happens in the first place.
For arrays, I agree. We very well may have arrays that we really want
to do magic things about. But even then I'd rather have a "don't
initialize this" flag for critical stuff that really *does* get
initialized some other way. Then we can grep for those things and be
more careful.
If somebody has big arrays on the stack, that's often a problem
anyway. It may be common in non-kernel code, but kernel code is very
special.
Linus
next prev parent reply other threads:[~2018-03-06 19:16 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-03 20:00 [PATCH RFC v9 0/7] Introduce the STACKLEAK feature and a test for it Alexander Popov
2018-03-03 20:00 ` [PATCH RFC v9 1/7] gcc-plugins: Clean up the cgraph_create_edge* macros Alexander Popov
2018-03-03 20:00 ` [PATCH RFC v9 2/7] x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls Alexander Popov
2018-03-05 16:41 ` Dave Hansen
2018-03-05 19:43 ` Laura Abbott
2018-03-05 19:50 ` Dave Hansen
2018-03-05 20:25 ` Peter Zijlstra
2018-03-05 21:21 ` Alexander Popov
2018-03-05 21:36 ` Kees Cook
2018-03-21 11:04 ` Alexander Popov
2018-03-21 15:33 ` Dave Hansen
2018-03-22 20:56 ` Alexander Popov
2018-03-26 17:32 ` Kees Cook
2018-03-26 17:43 ` Andy Lutomirski
2018-03-03 20:00 ` [PATCH RFC v9 3/7] gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack Alexander Popov
2018-03-03 20:00 ` [PATCH RFC v9 4/7] x86/entry: Erase kernel stack in syscall_trace_enter() Alexander Popov
2018-03-05 19:40 ` Dave Hansen
2018-03-05 20:06 ` Kees Cook
2018-03-05 20:15 ` Linus Torvalds
2018-03-05 21:02 ` Alexander Popov
2018-03-05 21:02 ` Kees Cook
2018-03-05 21:40 ` Linus Torvalds
2018-03-05 22:07 ` Linus Torvalds
2018-03-06 0:56 ` Kees Cook
2018-03-06 4:30 ` Linus Torvalds
2018-03-06 17:58 ` Andy Lutomirski
2018-03-06 7:56 ` [OLD PATCH] net: recvmsg: Unconditionally zero struct sockaddr_storage " Ingo Molnar
2018-03-06 8:08 ` Ingo Molnar
2018-03-06 15:16 ` Daniel Micay
2018-03-06 15:28 ` Daniel Micay
2018-03-06 18:56 ` Linus Torvalds
2018-03-06 19:07 ` Peter Zijlstra
2018-03-06 19:07 ` Ard Biesheuvel
2018-03-06 19:16 ` Linus Torvalds [this message]
2018-03-06 20:42 ` Arnd Bergmann
2018-03-06 21:01 ` Linus Torvalds
2018-03-06 21:21 ` Arnd Bergmann
2018-03-06 21:29 ` Linus Torvalds
2018-03-06 22:09 ` Arnd Bergmann
2018-03-06 22:24 ` Linus Torvalds
2018-03-06 21:36 ` Steven Rostedt
2018-03-06 21:41 ` Linus Torvalds
2018-03-06 21:47 ` Linus Torvalds
2018-03-06 22:29 ` Steven Rostedt
2018-03-06 22:41 ` Linus Torvalds
2018-03-06 22:52 ` Steven Rostedt
2018-03-06 23:09 ` Linus Torvalds
2018-03-12 8:22 ` Ingo Molnar
2018-03-12 9:00 ` Ard Biesheuvel
2018-03-12 9:21 ` Ingo Molnar
2018-03-06 21:47 ` Arnd Bergmann
2018-03-06 22:19 ` Linus Torvalds
2018-03-05 20:26 ` Peter Zijlstra
2018-03-03 20:00 ` [PATCH RFC v9 5/7] lkdtm: Add a test for STACKLEAK Alexander Popov
2018-03-03 20:00 ` [PATCH RFC v9 6/7] fs/proc: Show STACKLEAK metrics in the /proc file system Alexander Popov
2018-03-03 20:00 ` [PATCH RFC v9 7/7] doc: self-protection: Add information about STACKLEAK feature Alexander Popov
2018-03-05 19:34 ` [PATCH RFC v9 0/7] Introduce the STACKLEAK feature and a test for it Kees Cook
2018-03-05 19:42 ` Dave Hansen
2018-03-05 20:02 ` Kees Cook
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