Re: [RFC] perf: mmap2 not covering VM_CLONE regions

[Peter Zijlstra]

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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