Uma exhashazwa, lawa maphutha angavumela abahlaseli ukuthi bathole ukufinyelela okungagunyaziwe kulwazi olubucayi noma ngokuvamile babangele izinkinga.
Iqembu Abacwaningi bamanyuvesi aseChina nase-United States bathole ubungozi obusha kumaprosesa I-Intel iholela ekuvuzeni kolwazi ngenxa yemisebenzi yokuqagela ngokusebenzisa iziteshi zezinkampani zangaphandle, ezingasetshenziswa, isibonelo, ukuhlela isiteshi sokuxhumana esifihliwe phakathi kwezinqubo noma ukuthola ukuvuza ngesikhathi sokuhlasela kwe-Meltdown.
Ingqikithi yokuba sengozini iwushintsho ekubhaliseni kwe-EFLAGS processor, okwenzeka ngenxa yokwenziwa kokuqagela kwemiyalelo, kuthinta isikhathi esilandelayo sokwenziwa kwemiyalelo ye-JCC (gxuma lapho izimo ezishiwo zifinyelelwa).
Imisebenzi eqagelayo ayiqediwe futhi umphumela uyalahlwa, kodwa ushintsho olulahliwe lwe-EFLAGS lunganqunywa ngokuhlaziya isikhathi sokwenziwa semiyalelo ye-JCC. Imisebenzi yokuqhathanisa yangaphambi kwe-jump eyenziwe ngokuqagela, uma ukuqhathanisa kuphumelela, kubangela ukubambezeleka okuncane okungalinganiswa futhi kusetshenziswe njengesici sokufanisa okuqukethwe.
Ukuhlasela kokwenza kwesikhashana kuwuhlobo lokuhlasela olusebenzisa ukuba sengozini kobuchwepheshe bokuthuthukisa i-CPU. Ukuhlasela okusha kuvela ngokushesha. Isiteshi esiseceleni siyingxenye ebalulekile yokuhlasela kwesikhashana ukuze kukhishwe idatha.
Kulo msebenzi, sithole ubungozi obushintshe irejista ye-EFLAGS ekusebenzeni kwesikhashana okungase kube nomthelela oseceleni kumyalelo we-Jcc (Jump Condition Code) kuma-Intel CPUs. Ngokusekelwe ekutholeni kwethu, siphakamisa ukuhlasela okusha kwesiteshi eseceleni okusebenzisa isikhathi sokwenza kwesikhashana kanye nemiyalo ye-Jcc ukuze kulethwe idatha.
Lokhu kuhlasela kubethela idatha eyimfihlo ngokushintsha ukubhalisa okubangela ukuthi isikhathi sokwenza sihambe kancane futhi okungakalwa umhlaseli ukuze kuqondwe idatha. Lokhu kuhlasela akuncikile ohlelweni lwenqolobane.
Ngokungafani nokunye ukuhlasela okufanayo ngeziteshi zezinkampani zangaphandle, indlela entsha ayihlaziyi ushintsho ngesikhathi sokufinyelela kudatha egcinwe kunqolobane futhi ayigciniwe futhi ayidingi isinyathelo sokusetha kabusha irekhodi le-EFLAGS esimweni sokuqala, okwenza kube nzima ukuthola nokuvimbela ukuhlasela.
okwedemo, abacwaningi basebenzise okuhlukile kokuhlasela kwe-Meltdown, usebenzisa kuyo indlela entsha yokuthola ulwazi mayelana nomphumela womsebenzi wokuqagela. Ukusebenza kwendlela yokuhlela ukuvuza kolwazi ngesikhathi sokuhlasela kwe-Meltdown ikhonjiswe ngempumelelo kumasistimu ane-Intel Core i7-6700 kanye ne-i7-7700 CPUs endaweni eno-Ubuntu 22.04 kernel ne-Linux 5.15. Kuhlelo olune-Intel i9-10980XE CPU, ukuhlasela kube yimpumelelo ngokwengxenye.
Ukuba sengozini kwe-Meltdown kusekelwe eqinisweni lokuthi ngesikhathi sokwenziwa kokuqagela kwemiyalelo, iphrosesa ingafinyelela indawo yedatha eyimfihlo bese ilahla umphumela, njengoba amalungelo amisiwe avimbela ukufinyelela okunjalo enqubweni yomsebenzisi.
Kuhlelo, ibhulokhi eyenziwe ngokucabangela ihlukaniswa nekhodi eyinhloko ngokweqa okunemibandela, okuthi ezimweni zangempela kuhlale kubangelwa, kodwa ngenxa yokuthi isitatimende esinemibandela sisebenzisa inani lekhompyutha elingaziwa kumprosesa ngesikhathi sekhodi yokulungiselela. . ukubulawa, zonke izinketho zegatsha zenziwa ngokuqagela.
Ku-Meltdown yakudala, njengoba inqolobane efanayo isetshenziselwa imisebenzi eyenziwe ngokucatshangelwa njengemiyalo evame ukubulawa, kungenzeka ngesikhathi sokuqagela ukusetha omaka kunqolobane ebonisa okuqukethwe kwezingcezu ngazinye endaweni yenkumbulo evaliwe, bese isetshenziswa ngokujwayelekile. ikhodi yokunquma incazelo yayo ngokuhlaziywa kwesikhathi sokufinyelela kudatha egcinwe kunqolobane nengagciniwe.
Okuhlukile okusha kusebenzisa ushintsho ekubhaliseni kwe-EFLAGS njengophawu lokuvuza. Kudemo ye-Covert Channel, inqubo eyodwa ilungise idatha ethunyelwayo ukuze kushintshwe okuqukethwe kwerekhodi le-EFLAGS, futhi enye inqubo yahlaziya ushintsho ngesikhathi sokusebenza se-JCC ukuze kudalwe kabusha idatha ethunyelwe inqubo yokuqala.
Ekugcineni, uma unentshisekelo yokwazi okwengeziwe ngakho, ungaxhumana ne- imininingwane kusixhumanisi esilandelayo.