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CVE-2026-90047: Linux

7.8

CVSS 3.1

Няма данни

Вероятност да бъде експлоатирана в следващите 30 дни (EPSS)

Няма потвърждение

Атакува се

Няма данни

Време до експлоатация

Атакува се локално, без особени условия, с обикновен потребителски вход и без действие от потребителя.

    Описание

    Оригинално описание

    In the Linux kernel, the following vulnerability has been resolved: drm/xe: Don't hand out the flat CCS storage as usable VRAM get_flat_ccs_offset() reads the base of the flat CCS storage from the hardware, scales it by the number of enabled L3 nodes, and rounds the result up to 128K. Everything below that offset is then handed to the VRAM allocator as usable memory. Rounding a limit that means "usable memory ends here" upwards publishes whatever lies between the real base and the rounded one as free memory, and that memory belongs to the compression hardware. The scaled value has no reason to be 128K aligned, and on a Battlemage G21 with 16 GiB it is not: flat CCS base: raw 0x3fafff800, rounded 0x3fb000000 so the last 2 KiB of page 0x3fafff000 is CCS storage, in the allocator's pool. Whatever is allocated there gets that tail overwritten by the compression hardware, which needs no page-table entry, no buffer object and no GPU submission to do it, and does it before userspace exists. On this machine a Mesa VM's level-3 page table landed on that page on every cold boot. It lost the entry covering the compositor's batch-buffer heap, so the compositor's first submission faulted fetching its batch and gdm restarted it forever: a black screen on an otherwise working machine. Restarting gdm cleared it because the next VM's page tables were allocated somewhere else. Round down instead, to the page size the allocator works in. On this machine that excludes exactly one page. Reading the reserved page afterwards shows what had been writing it: [369] 0xcccc000000000000 [371] 0xcc77000000000000 [373] 0xcccc000000000000 [375] 0xcc77000000000000 compression metadata, two bytes per sixteen, sitting where the driver used to hand out memory. The assertion that should have caught this compares the offset against GSMBASE - ccs_size for equality. That value is 128K aligned, so it agrees with the rounded-up offset precisely when the base is not aligned - the check

    Засегнати продукти

    • Linux Linux: 37173392741c425191b959acb3adf70c9a4610c0 преди c96477e0cabf55bfbdf078078e9de1c8024f8060; 37173392741c425191b959acb3adf70c9a4610c0 преди 348c3db4f1520d36764ac8cae2492f50599714f6; 37173392741c425191b959acb3adf70c9a4610c0 преди 818bebeb63dd6bf5f4e07e145f6cdbace520a34c
    • Linux Linux: 6.13; преди 6.13; 6.18.51 до 6.18.*; 7.2.5 до 7.2.*; от 7.3 нататък

    История

    • 16 септември 2026 Публикувано

    Други уязвимости в Linux Linux

    Първоизточници

    CVE-2026-90047: Linux | freedomonline.bg