Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
bfs: Reconstruct file type when loading from disk
syzbot is reporting that S_IFMT bits of inode->i_mode can become bogus when the S_IFMT bits of the 32bits “mode” field loaded from disk are corrupted or when the 32bits “attributes” field loaded from disk are corrupted.
A documentation says that BFS uses only lower 9 bits of the “mode” field. But I can’t find an explicit explanation that the unused upper 23 bits (especially, the S_IFMT bits) are initialized with 0.
Therefore, ignore the S_IFMT bits of the “mode” field loaded from disk. Also, verify that the value of the “attributes” field loaded from disk is either BFS_VREG or BFS_VDIR (because BFS supports only regular files and the root directory).
Details
- Affected product:
- Ubuntu 20.04 ELS
- Affected packages:
- linux @ 5.4.0
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| Debian 11 | Released |
37 kernels
|
| Debian 11 cloud | Released |
17 kernels
|
| Debian 12 | Planned | — |
| Debian 13 | Will Not Fix | — |
| Ubuntu 22.04 | Planned | — |
| Ubuntu 22.04 AWS | Planned | — |
| Ubuntu 24.04 | Planned | — |
| Ubuntu 24.04 AWS | Planned | — |