Re: CVE-Request: AMD Bulldozer Linux ASLR weakness: Reducing entropy by 87.5%.

[Solar Designer <solar () openwall com>]

On Fri, Mar 27, 2015 at 01:11:41PM +0100, Hector Marco wrote:
> A bug in Linux ASLR implementation which affects some AMD processors has 
> been found. The issue affects to all Linux process even if they are not 
> using shared libraries (statically compiled). Grsecurity/PaX is also 
> affected.

spender's criticism, off Twitter:

<grsecurity> This new ASLR "weakness" with big 87.5% claims is a comedy of errors
<grsecurity> doesn't get the entropy count right for 32-bit in the email, copy+pasted the wrong entropy counts for 
grsec/PaX (it's 16, not 8)
<grsecurity> Further, the "fix" does absolutely nothing for local attackers and likely nothing for remote attackers 
either
<grsecurity> One leak of *any* library address from *any* service during the boot lifetime gives away the values
<grsecurity> And on vanilla kernels which still have no bruteforce protection whatsoever, this is less than a 
non-issue, & not worth dignifying in grsec

Alexander