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CVE-2026-74658: Linux

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    In the Linux kernel, the following vulnerability has been resolved: futex: Prevent robust futex exit race some more A robust futex unlock stores 0 over the whole futex value - wiping FUTEX_WAITERS - and wakes a single waiter. That wakeup is a one-shot notification: the protocol relies on its recipient to either acquire the futex (and eventually unlock while aware of the remaining contention) or re-arm FUTEX_WAITERS before sleeping again. If the woken waiter is killed before it can do either, the kernel must jump in and wake the next task down the line. This is a known complication of the futex protocol with a previous partial fix in commit ca16d5bee598 ("futex: Prevent robust futex exit race"). Unfortunately, that fix is insufficient. If a third task re-acquired the futex through the uncontended fast path in the meantime, the notification is lost: robust exit processing sees that it is owned by another task and does nothing, while the new owner sees no FUTEX_WAITERS when it unlocks and wakes nobody. The remaining waiters sleep forever behind a free futex: A owns the futex, B and C sleep in FUTEX_WAIT uval == A | FUTEX_WAITERS A robust unlock: store 0, FUTEX_WAKE(1) wakes B uval == 0 D fast path acquire: cmpxchg(0 -> D) uval == D, no FUTEX_WAITERS B killed before acting on the wakeup B exit walk, pending op: owner D != B -> no action D unlock: no FUTEX_WAITERS -> no wake C sleeps forever This is clearly a shortcoming in the implementation, which fails to keep the FUTEX_WAITERS bit consistent. Work around this by augmenting the robust list exit processing to also perform the extra wakeup if the futex word is owned by another thread but FUTEX_WAITERS is not set. This does not fix the problem of a non-contended take over/release and free sequence, which has been discussed for years and has be

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    • Linux Linux: ca16d5bee59807bf04deaab0a8eccecd5061528c преди 83b0f71d5a313a765754acab51d2ecc5de76e0b9; ca16d5bee59807bf04deaab0a8eccecd5061528c преди a1c2b7b86a946b6b172bce44d74553da2323a36c; ca16d5bee59807bf04deaab0a8eccecd5061528c преди 33bfa85458105d6169ebdb697f692b8bb8025bae; ca16d5bee59807bf04deaab0a8eccecd5061528c преди aa5c571901c6b22b58373693a4bf889ecab11ff5; ca16d5bee59807bf04deaab0a8eccecd5061528c преди 925628656b73b70930972ccde421de4f758d8650; ca16d5bee59807bf04deaab0a8eccecd5061528c преди 7b8c53263f8878bdd12c87e147ac6feca5c05211; ca16d5bee59807bf04deaab0a8eccecd5061528c преди 7cf710e70f9bb8ea75f759ebed09871801315992; ca16d5bee59807bf04deaab0a8eccecd5061528c преди 6d4514ca9cdf61fec4ec634cf50386f6f7e69748; 8dd558881e0f4d6942c19bd8f7b1a7c19becb59e; b90aa237f469c3575190a5e6a855b76ad1d2ce94; 3e24098da750991f75819069c79e090dfd029219; 2819f4030f43057238992a4adcd950d7c95aff65; 2c60b44d8ba9d62c2693d2692f118177f212b1a8; 82ca3ab31b9cf23b86436a85381e4c5757bc6b80; 3.16.82 преди 3.17; 4.9.264 преди 4.10; 4.14.158 преди 4.15; 4.19.87 преди 4.20; 5.3.14 преди 5.4; 5.4.1 преди 5.5
    • Linux Linux: 5.5; преди 5.5; 5.10.265 до 5.10.*; 5.15.216 до 5.15.*; 6.1.183 до 6.1.*; 6.6.152 до 6.6.*; 6.12.104 до 6.12.*; 6.18.45 до 6.18.*; 7.1.9 до 7.1.*; от 7.2 нататък

    История

    • 22 август 2026 Публикувано

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    CVE-2026-74658: Linux | freedomonline.bg