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CVE-2026-89767: 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: ovl: fix double end_creating() on the casefold-mismatch path ovl_create_real() releases the new dentry twice when the casefold consistency check fails. The S_IFDIR branch calls end_creating() and sets err, then falls through to the common out: label which calls end_creating() on the same dentry again: case S_IFDIR: newdentry = ovl_do_mkdir(ofs, dir, newdentry, attr->mode); err = PTR_ERR_OR_ZERO(newdentry); if (!err && ofs->casefold != ovl_dentry_casefolded(newdentry)) { pr_warn_ratelimited(...); end_creating(newdentry); /* first */ err = -EINVAL; } break; ... if (err) goto out; ... out: if (err) { end_creating(newdentry); /* second, same dentry */ return ERR_PTR(err); } end_creating() is end_dirop(), which does inode_unlock() on the parent and dput() on the dentry, so the parent directory's i_rwsem is unlocked twice and the dentry is put twice. The second unlock releases a lock that is not held, which is what wedges every later creation under that parent, and the second dput() drops a reference that was never taken. The branch was added by commit dfc7da402ccc ("ovl: Check for casefold consistency when creating new dentries") as a bare dput(), which already released the reference twice; commit fe497f0759e0 ("VFS: change vfs_mkdir() to unlock on failure.") converted both sites to end_creating(), adding the double unlock. This is reachable by an unprivileged user. The casefold consistency of the layers is validated at mount time in ovl_parse_layer(), and again on every lookup in ovl_lookup_single(), but ofs->workdir is the internal "work" subdirectory created inside the user-supplied workdir, and that subdirectory is not re-checked. Marking it casefolded after the mount therefore makes every ovl_create_temp() inherit the wrong state - and that path reaches ovl_create_real() through ovl_start_creating_temp(), which uses start_creating() with a generated name and

    Засегнати продукти

    • Linux Linux: dfc7da402ccc92d6e4b01a4778a3f15f2496b9af преди 2fa220bc0f84597cb6de665e5b5021c5901ddf00; dfc7da402ccc92d6e4b01a4778a3f15f2496b9af преди b1aa8ab78a8e87aee9e306971465408e059f839a; dfc7da402ccc92d6e4b01a4778a3f15f2496b9af преди 077ab8985ee278c3d8618182d335b0f0cd919e16
    • Linux Linux: 6.18; преди 6.18; 6.18.51 до 6.18.*; 7.2.4 до 7.2.*; от 7.3 нататък

    История

    • 11 септември 2026 Публикувано

    Други уязвимости в Linux Linux

    Първоизточници

    CVE-2026-89767: Linux | freedomonline.bg