Abacwaningi kwa-ETH Zurich bathuthukise ukuhlasela kwe-ZenHammer, okuhlukile kwesigaba se-RowHammer sokuhlasela ukuze kulungiswe okuqukethwe kwezingcezu ngazinye zememori yokufinyelela engahleliwe (i-DRAM), eguqulelwe ukusetshenziswa ezisekelweni ezinamaphrosesa e-AMD. Ukuhlaselwa kwe-RowHammer okwedlule kukhawulelwe kumasistimu asekelwe kuma-Intel processors, kodwa ucwaningo lubonise ukuthi ukonakala kwememori kungafinyelelwa nasezinkundleni ezinezilawuli zememori ye-AMD.
Indlela yaboniswa ezinhlelweni ze-AMD Zen 2 neZen 3 ezinenkumbulo ye-DDR4 evela kubakhiqizi abathathu abahamba phambili (i-Samsung, iMicron ne-SK Hynix). Ukuhlasela kudlula ngempumelelo indlela ye-TRR (Target Row Refresh) esetshenziswe kuma-memory chips, okuhloswe ngayo ukuvikela ekonakaleni kwamaseli enkumbulo emigqeni eseduze. Ngokusho kwabacwaningi, amasistimu asekelwe ku-AMD Zen 3 CPUs asengozini kakhulu kunezinhlelo ezinama-Intel Coffee Lake processors, futhi alula futhi asebenza kangcono ukuhlasela. Ezinhlelweni ze-AMD Zen 2, ukuhlanekezelwa kwamaseli kwafinyelelwa kuma-chips e-DDR7 ahloliwe angu-10 kwayi-4, nasezinhlelweni ze-Zen 3 kwabayisi-6 kwabayi-10. indlela eyakhelwe i-DDR4 yenziwe kabusha ngempumelelo kuma-memory chips e-DDR5 ahloliwe angu-4 kuphela kwayi-1, kuyilapho ithuba lokuhlasela ngokwalo lingabaliwe, kodwa lidinga ukuthuthukiswa kwamaphethini okufunda asebenza kahle afanele amadivayisi e-DDR10.
Ukuze basebenze nama-chips e-AMD, bakwazile ukujwayela ukuxhaphaza okwenziwe ngaphambilini okushintsha okuqukethwe okufakwe kuthebula lekhasi lememori (PTE, ukungena kwetafula lekhasi) ukuze bathole amalungelo e-kernel, ukudlula iphasiwedi/ukuhlolwa kwegunya ngokushintsha inkumbulo yenqubo ye-sudo. , futhi kulimaze ukhiye wasesidlangalaleni we-RSA-2048 ogcinwe kumemori ku-OpenSSH ukuze udale kabusha ukhiye oyimfihlo. Ukuhlaselwa kwekhasi lenkumbulo kukhiqizwe kabusha kuma-chips angu-7 kwangu-10 e-DDR4 ahloliwe, ukuhlasela kukakhiye we-RSA kuma-chips ayi-6, kanye nokuhlaselwa kwe-sudo kuma-chips angu-4, ngezikhathi zokuhlasela ze-164, 267, kanye nemizuzwana ye-209, ngokulandelana.
Indlela ingase futhi isetshenziselwe ukuhlasela isistimu ngokusebenzisa iziphequluli, ukwenza izinguquko emishinini ebonakalayo, noma ukuqalisa ukuhlasela phezu kwenethiwekhi. Ikhodi yomthombo yekhithi yamathuluzi ye-DARE yobunjiniyela bokuhlehla ukwakheka kwekheli kumemori ye-DRAM ifakwe ku-GitHub ngaphansi kwelayisensi ye-MIT, kanye namasethi amabili ezinsiza zokuhlola okudidayo kokonakala kancane enkumbulweni - ddr4_zen2_zen3_pub yama-DDR4 chips (Zen 2 ne-Zen 3) kanye ne-ddr5_zen4_pub yama-DDR5 chips (Zen 4), angasetshenziswa ukuhlola amasistimu awo ukuze ahlaseleke kalula.
Indlela ye-RowHammer isetshenziselwa ukuhlanekezela izingcezu, okusekelwe eqinisweni lokuthi kumemori ye-DRAM, okuwuhlu lwamaseli anezinhlangothi ezimbili ezihlanganisa i-capacitor kanye ne-transistor, ukwenza ukufundwa okuqhubekayo kwendawo yenkumbulo efanayo kuholela ekuguquguqukeni kwe-voltage futhi okudidayo okubangela ukulahlekelwa okuncane kwenkokhelo yamaseli angomakhelwane. Uma umfutho wokufunda uphakeme, khona-ke iseli elingumakhelwane lingase lilahlekelwe inani elikhulu ngokwanele lenkokhelo futhi umjikelezo wokuvuselela olandelayo ngeke ube nesikhathi sokubuyisela isimo sawo sokuqala, okuzoholela ekushintsheni kwenani ledatha egcinwe esitokisini. . Umcwaningi uhlonze izici zemephu yenkumbulo engokomzimba nokuvumelanisa nezindlela zokuvuselela inkumbulo ezisetshenziswa kumaphrosesa e-AMD, okwenze kwaba nokwenzeka ukuphinda kubhalwe ikheli le-DRAM lezinga eliphansi, ukunquma amakheli amaseli angomakhelwane, ukuthuthukisa izindlela zokudlula i-caching, nokubala amaphethini nemvamisa. yemisebenzi eholela ekulahlekelweni kwenkokhiso.
Ukuze bavikele ku-RowHammer, abakhiqizi bama-chip basebenzisa indlela ye-TRR (Target Row Refresh) evimba ukonakala kwamaseli ezimeni ezikhethekile, kodwa ayivikeli kuzo zonke izinketho zokuhlasela ezingase zibe khona. Indlela ephumelela kakhulu yokuvikela isalokhu ukusetshenziswa kwenkumbulo ngamakhodi wokulungisa amaphutha (ECC), okwenza kube nzima kakhulu, kodwa kungaqedi ngokuphelele, ukuhlasela kwe-RowHammer. Ukwandisa imvamisa yokuvuselelwa kwenkumbulo nakho kunganciphisa amathuba okuhlasela okuyimpumelelo.
I-AMD ishicilele umbiko ngodaba oluthi amaphrosesa e-AMD asebenzisa izilawuli zenkumbulo ezihambisana nokucaciswa kwe-DDR, futhi njengoba impumelelo yokuhlasela incike kakhulu kuzilungiselelo zesistimu nenkumbulo ye-DRAM, imibuzo mayelana nokuxazulula inkinga kufanele iqondiswe kubakhiqizi benkumbulo. kanye nezinhlelo Izindlela ezikhona zokwenza ukuhlasela kwesigaba se-Rowhammer kube nzima nakakhulu zihlanganisa ukusebenzisa inkumbulo ye-ECC, ukwandisa imvamisa yokuvuselelwa kwenkumbulo, ukukhubaza imodi yokuvuselela ehlehlisiwe, nokusebenzisa amaphrosesa anabalawuli abasekela imodi ye-MAC (Maximum Activate Count) ye-DDR4 (1st, 2nd kanye ne-3rd. isizukulwane se-AMD EPYC "Naple", "Rome" kanye "neMilan") kanye ne-RFM (Refresh Management) ye-DDR5 (isizukulwane sesine se-AMD EPYC).
Source: opennet.ru