Date: Wed, 2 Oct 2013 14:46:10 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Stephane Eranian <eranian@google.com>, LKML <linux-kernel@vger.kernel.org>,
        "mingo@elte.hu" <mingo@elte.hu>,
        "ak@linux.intel.com" <ak@linux.intel.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        David Ahern <dsahern@gmail.com>, Jiri Olsa <jolsa@redhat.com>,
        Hugh Dickins <hughd@google.com>, Kees Cook <keescook@chromium.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC] perf: mmap2 not covering VM_CLONE regions
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On Wed, Oct 02, 2013 at 02:39:53PM +0200, Ingo Molnar wrote:
>  - then there are timing attacks, and someone having access to a PMU
>    context and who can trigger this SHA1 computation arbitrarily in task 
>    local context can run very accurate and low noise timing attacks...
> 
>    I don't think the kernel's sha_transform() is hardened against timing 
>    attacks, it's performance optimized so it has variable execution time
>    highly dependent on plaintext input - which leaks information about the 
>    plaintext.

Typical user doesn't have enough priv to profile kernel space; once you
do you also have enough priv to see kernel addresses outright (ie.
kallsyms etc..).


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