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Date: Thu, 7 Oct 2010 12:42:48 -0300 From: Marcelo Tosatti <mtosatti@...hat.com> To: Avi Kivity <avi@...hat.com> Cc: Gleb Natapov <gleb@...antech.com>, Gleb Natapov <gleb@...hat.com>, kvm@...r.kernel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, mingo@...e.hu, a.p.zijlstra@...llo.nl, tglx@...utronix.de, hpa@...or.com, riel@...hat.com, cl@...ux-foundation.org Subject: Re: [PATCH v6 04/12] Add memory slot versioning and use it to provide fast guest write interface On Thu, Oct 07, 2010 at 12:00:13PM +0200, Avi Kivity wrote: > On 10/06/2010 10:08 PM, Gleb Natapov wrote: > >> Malicious userspace can cause entry to be cached, ioctl > >> SET_USER_MEMORY_REGION 2^32 times, generation number will match, > >> mark_page_dirty_in_slot will be called with pointer to freed memory. > >> > >Hmm. To zap all cached entires on overflow we need to track them. If we > >will track then we can zap them on each slot update and drop "generation" > >entirely. > > To track them you need locking. > > Isn't SET_USER_MEMORY_REGION so slow that calling it 2^32 times > isn't really feasible? Assuming it takes 1ms, it would take 49 days. > In any case, can use u64 generation count. Agree. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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