Kana dzikashandiswa, zvikanganiso izvi zvinogona kubvumira vanorwisa kuti vawane mukana usina mvumo kune ruzivo rwakadzama kana kuti kazhinji kukonzera matambudziko.
Munguva pfupi yapfuura a Google chengetedzo muongorori akaburitsa, kuburikidza ne blog post, iyo kuwanikwa kwekusagadzikana kutsva (CVE-2023-23583) paIntel processors, codenamed Reptar, iyo inobata akati wandei Intel desktop, nhare uye server CPUs, asi kunyanya makore masisitimu anomhanyisa akasiyana evashandisi 'makina.
Kunetseka "Reptar" inobvumira sisitimu kurembera kana kuparara kana ichiita mamwe maoparesheni pahurongwa hwevaenzi vasina kurongeka. Tichifunga, kusazvibata kunogona kushandiswa kukwidziridza ropafadzo kubva kumhete yechitatu yekudzivirira kuenda ku zero (CPL0) uye kutiza kubva munzvimbo dzakasarudzika, asi mamiriro ezvinhu aya haasati asimbiswa mukuita nekuda kwekunetsa kwekugadzirisa padanho re microarchitecture.
Chikwata cheGoogle chekuchengetedza ruzivo cheinjiniya chakashuma kusagadzikana kwaIntel, uyo akazvizivisa nhasi. Kuburikidza nekunyatsoshanda pamwe pakati peGoogle, Intel, uye vashandi veindasitiri, kudzikisira kwakaitwa uye vashandi veGoogle nevatengi vedu vanodzivirirwa.
Sekureva kwemutsvakurudzi, Kusagadzikana kunowanikwa muhuwandu hukuru hweIntel processor mhuri uye dambudziko rinonzi richaonekwa pachizvarwa chegumi Intel Core processors uye XNUMXrd chizvarwa Xeon Scalable processors, uyewo paXeon E/D/W processors.
About Reptar
Izvo zvinotaurwa kuti kushomeka imhaka yekuti kuitwa kwe "REP MOVSB" rairo yakanyorwa ne "REX" prefix. Redundant (a single-byte prefix) inoguma nemaitiro asina kutsanangurwa. The REX prefix inogona kupa mamwe mabhiti kune inotevera rairo yekushandisa se operands, nekudaro ichibvumira ese gumi nematanhatu anobvira general-chinangwa marejista kuti avharwe, uye aya mabhiti esarudzo anopa mukana wekukodha mamwe marejista echinangwa-chakawanda mukuraira kunotevera.
Muna Nyamavhuvhu, maitiro edu ekusimbisa akaburitsa chirevo chinonakidza. Akawana nyaya yekuwedzera yakarebesa REX prefixes kune yakagadziridzwa FSRM "rep movs" oparesheni yaiita sekukonzera zvisingafungidzirwe.
Takaona mamwe maitiro anoshamisa panguva yekuyedzwa. Semuyenzaniso, matavi kunzvimbo dzisingatarisirwi, matavi asina zvimiso asina kufuratirwa, uye processor haicharekodha nemazvo iyo yekurairidza pointer xsaveo yekufona mirairo.
Sezvineiwo, pakuedza kunzwisisa kuti chii chaiitika, isu taiona debugger ichitaura zvisingaite.
Nyaya yakawanikwa panguva yekuyedzwa kwekutanga kwekutanga, izvo zvinofanirwa kufuratirwa, asi mukuita zvakakonzera zvisinganzwisisike mhedzisiro, sekuregeredza matavi asina magumo uye kutyora pointer kuchengetedza mu xsave uye kufona mirairo. Imwezve ongororo yakaratidza kuti kuwedzera chivakashure che "REP MOVSB" kukonzeresa huwori mune zviri mukati me ROB (ReOrder Buffer) inoshandiswa kuhodha mirairo.
Chinhu chinonakidza che x86 ndechekuti decoding yekuraira inowanzo zorora. Kana iwe ukashandisa chivakashure chisinganzwisisike kana kupesana nemamwe maprefixes, hapana zvakawanda zvichaitika, kazhinji zvinongoregeredzwa.
Chokwadi ichi dzimwe nguva chinobatsira; Macompilers anogona kushandisa dundant prefixes kupedha rairo imwe chete kusvika kune inodiwa kurongeka muganho.
Iko kukanganisa kunofungidzirwa kuve nekuda kwekuverenga kusiri iko kwehukuru hwe "MOVSB" rairo ine prefix yakawandisa, inotungamira mukutyorwa kwekutaura kwemirairo yakanyorwa kune ROB buffer mushure meMOVSB uye kutamiswa kweinongedzo yekuraira.
Iyi desynchronization inogona kugumira pakukanganiswa kwekuverenga kwepakati nekuzotevera kudzoreredzwa kweiyo integral state. Asi kana iwe ukavharira akawanda macores kana SMT tambo panguva imwe chete, inogona kukonzera kukuvadza kwakakwana kune iyo microarchitecture kuti iite kuti iparare.
Ongororo yemukati yeIntel yakaratidzawo mukana wekusagadzikana kushandiswa kuwedzera maropafadzo pasi pemamwe mamiriro.
Chekupedzisira, zvakakodzera kutaura kuti kuyedza kutendeseka kwemasystem, basa rakabudiswa izvo zvinogadzira mamiriro ekuratidzwa kwekusagadzikana, mukuwedzera kune chokwadi chekuti kusagadzikana kuri mubvunzo kwakagadziriswa muiyo microcode update 20231114.
Kana uri kufarira kuziva zvakawanda nezvazvo, unogona kutarisa ruzivo mu chinotevera chinongedzo.