namespace: check the mounts before reading their parents in pivot_root()
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Linux | Linux | affected |
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| Linux | Linux |
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| Linux | Linux Kernel |
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| Linux | Linux Kernel |
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| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-4904-1 | linux-6.12 security update |
Ubuntu USN |
USN-9018-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-9018-2 | Linux kernel (HWE) vulnerabilities |
Ubuntu USN |
USN-9019-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-9020-1 | Linux kernel vulnerabilities |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.177% probability within 30 days)
Key SSVC decision points have not yet been added.
| Type | Values Removed | Values Added |
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| Weaknesses | CWE-416 |
| Type | Values Removed | Values Added |
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| Weaknesses | CWE-825 | |
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| Metrics |
threat_severity
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cvssV3_1
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| First Time appeared |
Linux linux
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| Vendors & Products |
Linux linux
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| Weaknesses | CWE-416 |
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| Description | In the Linux kernel, the following vulnerability has been resolved: namespace: check the mounts before reading their parents in pivot_root() path_pivot_root() reads the parents of new_root and of the caller's root and checks whether they are shared before it checks that either mount is in the caller's mount namespace. Only namespace_sem is held. That's fine for a mount that is in the caller's mount namespace. But new_root can be a file descriptor to a mount that has been unmounted and that only the file descriptor keeps alive. If that mount stayed attached to its parent when it was unmounted nothing pins the parent for it. The final mntput() of the parent unhooks the children under mount_lock alone and frees the parent afterwards: pivot_root() close(fd), last ref on the parent ------------ --------------------------------- ex_parent = new_mnt->mnt_parent mntput_no_expire_slowpath() __umount_mnt(new_mnt) cleanup_mnt() call_rcu() IS_MNT_SHARED(ex_parent) BUG: KASAN: slab-use-after-free in path_pivot_root+0xf1a/0x1840 Read of size 4 at addr ffff8881047382f8 by task pivot_widen/157 path_pivot_root+0xf1a/0x1840 __x64_sys_pivot_root+0x165/0x190 The same goes for the caller's root via chroot(). Both outcomes of the check end in EINVAL so nothing but the read itself goes wrong. It's the same thing commit bb4609405752 ("statmount: read the parent of an unmounted mount under mount_lock") fixed for statmount(). Check that both mounts are in the caller's namespace before their parents are read. Every path returns EINVAL either way. | |
| Title | namespace: check the mounts before reading their parents in pivot_root() | |
| First Time appeared |
Linux
Linux linux Kernel |
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| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
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