CVE-2026-31577
Published: April 25, 2026Last modified: June 2, 2026
Description
In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map The DAT inode's btree node cache (i_assoc_inode) is initialized lazily during btree operations. However, nilfs_mdt_save_to_shadow_map() assumes i_assoc_inode is already initialized when copying dirty pages to the shadow map during GC. If NILFS_IOCTL_CLEAN_SEGMENTS is called immediately after mount before any btree operation has occurred on the DAT inode, i_assoc_inode is NULL leading to a general protection fault. Fix this by calling nilfs_attach_btree_node_cache() on the DAT inode in nilfs_dat_read() at mount time, ensuring i_assoc_inode is always initialized before any GC operation can use it.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 5.5 |
| Attack Vector | LOCAL |
| Attack complexity | LOW |
| Privileges required | LOW |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | NONE |
| Integrity impact | NONE |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | linux-lts | Fixed (6.1.175-r0) |
| 25 LTS | linux-lts | Fixed (6.12.85-r0) | |
| Stream | linux-lts | Fixed (6.12.85-r0) |
References
- https://git.kernel.org/stable/c/41de342278ae025c99cc8d33648773f05e306cf1
- https://git.kernel.org/stable/c/449ec5fc99f45974525ba9eea16b6670c45cd363
- https://git.kernel.org/stable/c/4a4e0328edd9e9755843787d28f16dd4165f8b48
- https://git.kernel.org/stable/c/6637bbcfb59df5b732a79e5ab1a74886a0b93d59
- https://git.kernel.org/stable/c/7318e3549518ce8f14776a489d86488d80d7e2c8
- https://git.kernel.org/stable/c/7902b1df1520a0880bcda7a3704cfacd17905a83
- https://git.kernel.org/stable/c/837c7a59fb58f81b0db33848357f6a5d0d1250ad
- https://git.kernel.org/stable/c/97fb7afec404912d967a7d4715f37742666b3084
- https://git.kernel.org/stable/c/c36e206f302f1ddefed92d09ecbba070e1ae079e