Date: Sun, 3 Jun 2018 08:31:30 +0200 From: Greg KH <gregkh@...uxfoundation.org> To: procmem <procmem@...eup.net> Cc: kernel-hardening@...ts.openwall.com Subject: Re: Nethammer and kernel network drivers 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 We have only found very outdated network drivers using clflush (old 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
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