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CVE-2026-98980: Linux

8.8

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: namei: don't reveal overmounted entries in refwalk In rcuwalk the dentry is validated before it is accepted. step_into() step_into() rechecks d_seq and __follow_mount_rcu() rechecks mount_lock. An entry that gets unlinked in between causes the lookup to retry and miss. A refwalk doesn't do this. lookup_fast() takes a reference on the hashed dentry and simply accepts it. So an unlink that happens after the reference was taken isn't seen by refwalk. That's fine for a simple file. We just happened to open it before it was unlinked, no problem. For a mountpoint and specifically a locked mountpoint it very much isn't. The unlink detaches all mounts and then removes the name. Any refwalk that hasn't traversed the mounts yet simply reveals the underlying entry. It's a very narrow window but it can be hit: reads of a covered file in 60 s, 3 walkers, ~15000 unlinks no widening 27 that step + 200 us 3741 See the appended patch for a more reliable reproducer. So check the entry after step_into(). unlink(), rmdir() and rename() mark the dentry with dont_mount() before they detach the mounts and remove the dentry. So a dentry that is marked with DCACHE_CANT_MOUNT and is unhashed by the time its mounts were looked at is a name that was unlinked under the refwalk. DCACHE_CANT_MOUNT is read after the mounts were looked up and it is set before they are detached by detach_mounts(). A refwalk that missed the mounts will see DCACHE_CANT_MOUNT. Plain d_unlinked() is fine. A rename takes the dentry off its hash chain but ___d_drop() leaves d_hash.pprev set. So only __d_drop() and a rename over the dentry unhash it. The only move that flips IS_ROOT splices in a disconnected alias. That doesn't have DCACHE_CANT_MOUNT set. Add the to step_into_slowpath(). ".." and LOOKUP_DOWN may legitimately land on an unhashed directory. A refwalk that crossed onto a mount has path.mnt different from nd->p

    Засегнати продукти

    • Linux Linux: 8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe преди e2b10181d913b4efa3a8dc67a532f859aa5f95e0; 8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe преди 5f97df8ca7fadf5b53954f50073445ba193902c0; 8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe преди b43ff2deef48260bfbdc0dcb520f7929bd3e4007; 8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe преди 8189ab688f5a2c745dc90b63374da02f213d6994
    • Linux Linux: 3.18; преди 3.18; 6.12.113 до 6.12.*; 6.18.57 до 6.18.*; 7.2.11 до 7.2.*; от 7.3 нататък

    История

    • 23 октомври 2026 Публикувано

    Други уязвимости в Linux Linux

    Първоизточници

    CVE-2026-98980: Linux | freedomonline.bg