CVE-2026-98982
Açıklama (NVD)
In the Linux kernel, the following vulnerability has been resolved: namespace: don't let a pseudo dentry become the root of a mount d_alloc_pseudo() hands out dentries for pipes, sockets and other files that are never anyone's child or parent. They carry DCACHE_NORCU and dentry_free() frees them right away because no lockless path walk can ever reach them. That holds as long as such a dentry isn't the root of a mount. But bind mounting /proc/self/fd/<fd> of such a file does exactly that. Most callers of alloc_file_pseudo() put their files on kernel-internal mounts and may_copy_tree() refuses those. bpf_token_create() doesn't. It places the token file on the bpffs mount the caller handed it and that mount is in the caller's mount namespace so the clone goes through: mount --bind /proc/self/fd/<token> <file> open_tree(tokfd, "", AT_EMPTY_PATH | OPEN_TREE_CLONE) + move_mount() __follow_mount_rcu() then loads ->mnt_root of that mount, reads d_seq and d_flags of the dentry and only then checks mount_lock. The dentry can be gone by then. The final mntput() of an unmounted parent unhooks a child that stayed attached to it under mount_lock alone. When the child's holder does the final put right after that the root is dput() and freed immediately while a walker that found the mount hashed still looks at it. Refuse to clone a mount with a DCACHE_NORCU dentry as its root. Nothing sensible can be done with a bind mount of a bpf token anyway.
Yayın: 23.10.2026 · Son değişiklik: 24.10.2026
CVSS 3.1 metrikleri
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
| Saldırı vektörü | Yerel |
| Karmaşıklık | Düşük |
| Gereken yetki | Düşük |
| Kullanıcı etkileşimi | Gerekmez |
| Kapsam | Değişmez |
| Gizlilik | Yüksek |
| Bütünlük | Yüksek |
| Erişilebilirlik | Yüksek |
Hesaplanan temel puan: 7.8. CVSS hesaplayıcıda incele