Michael S. Tsirkin wrote: > On Mon, Jun 22, 2009 at 09:04:48AM -0400, Gregory Haskins wrote: > >> Sorry, Michael. I missed that you had other comments after the >> grammatical one. Will answer inline >> >> Michael S. Tsirkin wrote: >> >>> On Mon, Jun 22, 2009 at 08:13:48AM -0400, Gregory Haskins wrote: >>> >>> >>> >>>> If thats true, we are in trouble ;) >>>> >>>> >>> I think it works at least on x86: >>> http://en.wikipedia.org/wiki/Packed#x86_and_x86-64 >>> >>> >> Right, understood. What I meant specifically is that if the (void*)val >> pointer is allowed to be misaligned we are in trouble ;). I haven't >> studied the implementation in front of the MMIO callback recently, but I >> generally doubt thats the case. More than likely this is some buffer >> that was kmalloced and that should already be aligned to the machine word. >> >> Kind Regards, >> -Greg >> >> > > Yes, from what I saw of the code I think it can be BUG_ON. > Avi? > > The question to ask is whether a guest can influence that condition. If they can, its an attack vector to crash the host. I suspect they can't, however. Therefore, your recommendation is perhaps a good approach so this condition cannot ever go unnoticed. Avi? -Greg
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