Ƙungiyar masu bincike daga jami'o'in Sin da Amurka sun gano wani sabon rauni a cikin na'urori masu sarrafa Intel wanda ke haifar da ɓarna na ɓangare na uku game da sakamakon ayyukan hasashe, wanda za'a iya amfani dashi, alal misali, don tsara hanyar sadarwa ta ɓoye tsakanin matakai ko gano yoyon fitsari yayin harin Meltdown.
Ma'anar raunin shine cewa canji a cikin rajistar mai sarrafawa na EFLAGS wanda ke faruwa sakamakon hasashe na aiwatar da umarni yana shafar lokacin aiwatar da umarnin JCC na gaba (tsalle lokacin da ƙayyadaddun yanayi suka cika). Ayyukan ƙididdiga ba su cika ba kuma an watsar da sakamakon, amma ana iya ƙayyade canjin EFLAGS da aka jefar ta hanyar nazarin lokacin aiwatar da umarnin JCC. Ayyukan kwatanta da aka yi a cikin yanayin hasashe kafin canji, idan an yi nasara, yana haifar da ɗan jinkiri wanda za'a iya aunawa da amfani da shi azaman alamar zaɓin abun ciki.
Ba kamar sauran hare-haren tashoshi masu kama da juna ba, sabuwar hanyar ba ta yin nazarin sauye-sauyen lokacin samun damar yin amfani da bayanan da ba a adana ba kuma baya buƙatar matakin sake saita rajistar EFLAGS zuwa yanayin farko, wanda ke da wahala a gano tare da toshe harin. A matsayin nuni, masu binciken sun aiwatar da bambance-bambancen harin Meltdown, ta hanyar amfani da sabuwar hanya don samun bayanai game da sakamakon wani aiki na hasashe. An nuna nasarar aiwatar da hanyar don tsara kwararar bayanai yayin harin Meltdown akan tsarin tare da Intel Core i7-6700 da i7-7700 CPU a cikin yanayi tare da Ubuntu 22.04 da Linux kernel 5.15. A kan tsarin da ke da Intel i9-10980XE CPU, an kai harin ne kawai a wani yanki.
Rashin lahani na Meltdown ya dogara ne akan gaskiyar cewa yayin aiwatar da hasashe na umarni, mai sarrafa na'ura zai iya shiga wurin bayanan sirri sannan ya watsar da sakamakon saboda abubuwan da aka saita sun hana irin wannan damar daga tsarin mai amfani. A cikin shirin, da speculatively kashe block an rabu da babban code ta wani reshe na sharadi, wanda a cikin hakikanin yanayi ko da yaushe gobara, amma saboda gaskiyar cewa sharadi bayani yana amfani da wani ƙididdiga darajar da processor bai sani ba a lokacin preemptive kisa. code, duk reshe zažužžukan ana aiwatar da speculatively.
A cikin sigar gargajiya ta Meltdown, tunda ana amfani da cache iri ɗaya don ayyukan da aka aiwatar da ƙima kamar yadda ake aiwatar da umarni na yau da kullun, yana yiwuwa yayin aiwatar da hasashe don saita alamomi a cikin cache waɗanda ke nuna abubuwan da ke cikin rago ɗaya a cikin rufaffiyar ƙwaƙwalwar ajiya, sannan Ƙayyade ma'anar su a cikin lambar da aka aiwatar ta al'ada ta hanyar nazarin lokacin samun damar cache da bayanan da ba a adana ba. Sabuwar bambance-bambancen yana amfani da canji a cikin rijistar EFLAGS azaman alamar zubewa. A cikin zanga-zangar tasha mai ɓoye, ɗayan tsari ya canza bayanan da aka watsa don ƙirƙirar yanayi don canza abubuwan da ke cikin rajistar EFLAGS, kuma wani tsari ya bincika canjin lokacin aiwatar da umarnin JCC don sake ƙirƙirar bayanan da aka watsa ta hanyar farko.
source: budenet.ru