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CVE-2026-89689: Linux

9.8

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 по мрежата, без особени условия, без вход и без действие от потребителя.

    Описание

    Оригинално описание

    In the Linux kernel, the following vulnerability has been resolved: nfsd: don't free session slots that are still in use nfsd4_sequence() can free the very slot it is currently processing. When the session shrinker has reduced se_target_maxslots below se_fchannel.maxreqs, the shrink path checks three conditions before calling free_session_slots(): 1. se_target_maxslots < maxreqs (shrink was advertised) 2. slot->sl_generation == se_slot_gen (slot is up-to-date) 3. seq->maxslots <= se_target_maxslots (client acknowledges) However, seq->slotid is never checked against se_target_maxslots. A client using a slot in the range [se_target_maxslots, maxreqs) can satisfy all three conditions: its slot has the current generation (set by a prior SEQUENCE), and it sends sa_highest_slotid <= se_target_maxslots to acknowledge the reduction. free_session_slots() then kfrees every slot at index >= se_target_maxslots, including the caller's own slot. The function continues to write sl_seqid, sl_flags, sl_generation, and stores the dangling pointer in cstate->slot. Later, nfsd4_store_cache_entry() copies up to maxresp_cached bytes of the compound reply into the freed sl_data[] array, corrupting whatever slab object now occupies that address. Additionally, a concurrent thread processing SEQUENCE on a different high-numbered slot can have its slot freed out from under it. NFSD4_SLOT_INUSE is set under nn->client_lock before the lock is released, so any concurrent thread past SEQUENCE will have its slot marked. However, free_session_slots() does not check NFSD4_SLOT_INUSE before freeing. Fix both problems by: 1. Checking that the current request's slotid is below the shrink boundary. 2. Scanning slots in the to-be-freed range for NFSD4_SLOT_INUSE and deferring the shrink if any are active.

    Засегнати продукти

    • Linux Linux: fc8738c68d0bbf5033dd98b4f63d277ecbd49fd7 преди 72d40b103bb03f0124d3a3c8f71a30cbafaf6afa; fc8738c68d0bbf5033dd98b4f63d277ecbd49fd7 преди b449b134e7762ddf98653a4b1d3e76d2d212ea64; fc8738c68d0bbf5033dd98b4f63d277ecbd49fd7 преди f5d22e372f4ac3eb287037a488c29691d52a6330
    • Linux Linux: 6.14; преди 6.14; 6.18.50 до 6.18.*; 7.2.4 до 7.2.*; 7.3 до *

    История

    • 11 септември 2026 Публикувано

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    Първоизточници

    CVE-2026-89689: Linux | freedomonline.bg