Date: Sun, 3 Jun 2018 13:23:28 +0000 From: procmem <procmem@...eup.net> To: Greg KH <gregkh@...uxfoundation.org> Cc: kernel-hardening@...ts.openwall.com Subject: Re: Nethammer and kernel network drivers Greg KH: > On Sat, Jun 02, 2018 at 05:41:09PM +0000, procmem wrote: >> Hello. Daniel provided more details on the problematic areas of the >> kernel and I quote what he said verbatim: >> >> >>> We have only found very outdated network drivers using clflush (old >>> windows ndis code). On ARM there are many drivers using uncached memory. >>> However, we have so far failed to produce enough memory traffic on ARM >>> to trigger a bit flip with Nethammer on any ARM device. >>> It should be possible though if you can make the ARM device handle >>>> =300MBit/s. >>> And that's the most plausible scenario. >>> >>> Anyway, searching for clflush or use of uncached memory is a good idea >>> to locate the critical spots. >>> >>> Intel CAT is (we believe) not used anywhere yet. And we must be careful >>> when it gets to the point where we introduce usage of CAT for QoS >>> mechanisms. >>> >>> However, my intuition tells me that most systems are not even vulnerable >>> to Rowhammer in the first place. Although the only prevalence studies we >>> have suggest otherwise (they find 60-80% are affected). > > So Linux is not vulnerable to this at all? That's good to know, thanks > for following up with this. > > greg k-h > I interpreted this to mean that there is a major problem with ARM drivers but the only backstop is the current gen of hardware being underpowered. Also it would be best to put a kernel comment about sec implications of Intel CAT for those who want to enable/use it IMHO.
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