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CVE-2026-89927: Linux

7.1

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, без вход и без действие от потребителя.

    Описание

    Оригинално описание

    In the Linux kernel, the following vulnerability has been resolved: KVM: x86: hyper-v: Clamp stimer deadline to avoid livelock Fix an issue where userspace or the guest can program an Hyper-V synthetic timer to have a deadline in the past via integer overflow, preventing the CPU from making progress and triggering an RCU stall. Hyper-V's SynIC exposes 4 per-vCPU synthetic timers to the guest, which are emulated by KVM. Each is programmed through the HV_X64_MSR_STIMERi_CONFIG and HV_X64_MSR_STIMERi_COUNT MSRs. Depending on CONFIG, COUNT represents either the absolute expiration time or the period of a periodic timer, both expressed in 100ns ticks. These timers may be set both by the guest (WRMSR) and the host (KVM_SET_MSRS). When the timer is enabled, stimer_start() translates COUNT to an absolute monotonic deadline and arms an hrtimer. If COUNT is set to a value close to U64_MAX, the deadline calculation can overflow. ktime_add_ns(ktime_now, 100 * (stimer->exp_time - time_now)) This can result in a CPU livelock. stimer_start() arms the timer via hrtimer_start() with a deadline in the past, which causes it to immediately fire. The stimer callback then raises KVM_RQ_HV_STIMER, with the intention of causing KVM to deliver a synthetic interrupt on the next vCPU guest enter. Then, once userspace issues KVM_RUN, vcpu_enter_guest() consumes the request, calling kvm_hv_process_stimers(). This would normally disable the timer via stimer_expiration() once the deadline is in the past. However, the deadline comparison is done between the KVM reference counter and stime->exp_time, which is a big value close to U64_MAX, so this never happens for a few thousand years. kvm_hv_process_timers() then re-arms the timer via stimer_start(), since it was not disabled, which again fires immediately. Before entering the guest, kvm_vcpu_exit_request() checks kvm_request_pending(), which returns true due to the newly raised KVM_REQ_HV_STIMER. Then vcpu_enter_guest() aborts the gue

    Засегнати продукти

    • Linux Linux: 1f4b34f825e8cef6f493d06b46605384785b3d16 преди a4665762388750e08df99baabe5fce2a21d1423e; 1f4b34f825e8cef6f493d06b46605384785b3d16 преди 61954727ee08f026f5e1c9ee69e1b404a68f2f7a; 1f4b34f825e8cef6f493d06b46605384785b3d16 преди 8aa467fe757d8cb2278e98d7fbf44fc05eb0dbf8; 1f4b34f825e8cef6f493d06b46605384785b3d16 преди 8e19ded84336891646b31375720717635f0fdd90; 1f4b34f825e8cef6f493d06b46605384785b3d16 преди 6a8ba9213cce613455b1502ee0fd178656bf617b; 1f4b34f825e8cef6f493d06b46605384785b3d16 преди 3097582b73a8ed1cd6f6790fa78706f4a79b5a49; 1f4b34f825e8cef6f493d06b46605384785b3d16 преди bdb732ebee545b7e3bee7060efc754a8d99818b9; 1f4b34f825e8cef6f493d06b46605384785b3d16 преди 0ca49fbd2883cd53d32d85b50feef17fa04d0fbf
    • Linux Linux: 4.5; преди 4.5; 5.10.270 до 5.10.*; 5.15.221 до 5.15.*; 6.1.188 до 6.1.*; 6.6.157 до 6.6.*; 6.12.110 до 6.12.*; 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-2026-89927: Linux | freedomonline.bg