CVSS 3.1
Вероятност да бъде експлоатирана в следващите 30 дни (EPSS)
Атакува се
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: namespace: a mount that copy_tree() leaves out can't take over a lock Since commit c62a4766937e ("move_mount: transfer MNT_LOCKED") a mount can be moved beneath a locked mount. The lock moves from the old cover to the new mount which takes over the job of hiding what's under it and the old cover can be unmounted. That works as long as the new mount stays. But the caller picks the new mount and copy_tree() leaves a mount of a mount namespace file out of every copy made without CL_COPY_MNT_NS_FILE, together with everything mounted on it, and never looks at MNT_LOCKED. unshare(CLONE_NEWNS) and mount propagation make such copies. So a task that is root in its own user namespace gets rid of a locked cover on a file without a race and without touching the filesystem below it. It makes a child with a mount namespace of its own, binds the child's /proc/<pid>/ns/mnt beneath the cover with MOVE_MOUNT_BENEATH, which hands the lock to that bind, and calls unshare(CLONE_NEWNS). The new mount namespace has nothing on the file. That's the usual way to mask a single file, a bind of /dev/null or of an empty file. With a bind of an ordinary file the file stays covered. copy_tree() already refuses to leave out a locked unbindable mount with -EPERM since commit df7342b24018 ("mount: Don't allow copying MNT_UNBINDABLE|MNT_LOCKED mounts"). Do the same for a locked mount of a mount namespace file. That also covers a tree copied with CL_COPY_MNT_NS_FILE and attached into a mount namespace of another user namespace where lock_mnt_tree() locks it. Note that unshare(CLONE_NEWNS) and clone(CLONE_NEWNS) fail with EPERM from such a mount namespace from then on. The mount can't be left out and it can't be unmounted. And refuse to move a mount of a mount namespace file beneath a locked mount in the first place. Otherwise the task ends up with a mount it can't unmount and an unshare() that fails for good. Chris also found a s
Засегнати продукти
- Linux Linux: c62a4766937edec2962d52e583276b459b739f2d преди bd71d33923b9d6216bcee44331dd37142b0a8441; c62a4766937edec2962d52e583276b459b739f2d преди 69fbe94f80bc423613fa18dae6656757423732a2
- Linux Linux: 7.1; преди 7.1; 7.2.13 до 7.2.*; от 7.3 нататък
История
- 28 октомври 2026 Публикувано