Adịghị ike na e2fsck mgbe ị na-ahazi akwụkwọ ndekọ aha ahaziri ahazi

N'ime ngwa e2fsck ewepụtara dịka akụkụ nke ngwugwu mmmmmmmmmmmm, mara adịghị ike (CVE-2019-5188), nke na-enye gị ohere ime koodu onye mwakpo mgbe ị na-elele sistemụ faịlụ nwere akwụkwọ ndekọ aha ahaziri ahazi. Ekwenyere adịghị ike ahụ na mwepụta 1.43.3 ruo 1.45.4. Edobere adịghị ike na mmelite e2fsck 1.45.5. Na ngwa nkesa nsogbu ahụ ka na-adazighị (Debian, Arch Linux, SUSE/mepeeSUSE, Ubuntu, RHEL).

A na-akpata adịghị ike ahụ site na njehie na mutate_name () ọrụ na rehash.c faịlụ, nke a na-eji emeghachite tebụl hash jikọtara ya na ndekọ ndekọ, na-ahụ na faịlụ niile dị na ndekọ ahụ kwekọrọ na ndekọ. Nrụrụ aka nke nhazi hash_entry jikọtara ya na akwụkwọ ndekọ aha nwere ike ime ka onye mwakpo na-ede data na mpaghara na-abụghị ebe nchekwa ekenyela. Ọ bụrụ na achọpụtara ọtụtụ faịlụ nwere otu aha na tebụl hash ka ejikọtara ya na ndekọ aha, ọrụ e2fsck na-edegharị faịlụ oyiri site na ịgbakwunye ~ 0, ~ 1, wdg na aha ahụ. Iji chekwaa aha ọhụrụ nwa oge n'oge a na-agbanwe aha ahụ, a na-ekenye ihe nchekwa nke 256 bytes n'ogo n'elu ngwugwu ahụ.

A na-ekpebi nha data a ga-edegharị site na okwu "entry->name_len & 0xff", mana uru ntinye ->name_len na-ebufe site na nhazi dị na diski kama gbakọọ site na aha aha ahụ kpọmkwem. Ọ bụrụ na nha ahụ bụ efu, mgbe ahụ, nchịkọta nchịkọta na-ewe uru -1 na ọnọdụ a na-emepụta maka integer jubigara ókè site na ala ala nke ihe nchekwa (integer underflow) ma degharịa data ndị ọzọ na nchịkọta na uru "~ 0". Maka sistemụ 64-bit, a na-enyocha nrigbu nke adịghị ike dị ka ihe na-agaghị ekwe omume ma ọ nweghị ihe mgbochi ọ bụla na nha njupụta (ulimit -s unlimited). Maka sistemụ 32-bit, a na-ahụta nrigbu ga-ekwe omume, mana nsonaazụ ya dabere na otu onye na-achịkọta ihe siri chịkọta ya.

Iji mee mwakpo, onye na-awakpo kwesịrị imebi data ahụ n'ụzọ ụfọdụ na nkebi ya na ext2, ext3 ma ọ bụ ext4 faịlụ. Ebe ọ bụ na ọrụ a chọrọ ikike ndị superuser, adịghị ike ahụ na-ebute ihe iyi egwu mgbe akụrụngwa e2fsck na-enyocha draịva mpụga ma ọ bụ onyonyo FS natara na mpụga.

isi: opennet.ru

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