Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
ceph: prevent use-after-free in encode_cap_msg()
In fs/ceph/caps.c, in encode_cap_msg(), “use after free” error was caught by KASAN at this line - ‘ceph_buffer_get(arg->xattr_buf);’. This implies before the refcount could be increment here, it was freed.
In same file, in “handle_cap_grant()” refcount is decremented by this line - ‘ceph_buffer_put(ci->i_xattrs.blob);’. It appears that a race occurred and resource was freed by the latter line before the former line could increment it.
encode_cap_msg() is called by __send_cap() and __send_cap() is called by ceph_check_caps() after calling __prep_cap(). __prep_cap() is where arg->xattr_buf is assigned to ci->i_xattrs.blob. This is the spot where the refcount must be increased to prevent “use after free” error.
Details
- Affected product:
- AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 6 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 6 ELS , CloudLinux 7 ELS , Debian 10 ELS , Oracle Linux 6 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , TuxCare 9.8 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- linux-hwe @ 4.15.0 (+22 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| AlmaLinux 9.6 ESU | Planned | — |
| Amazon Linux 2023 | Planned | — |
| Amazon Linux 2 5.10 | Will Not Fix | — |
| CentOS 7 ELS | Released |
11 kernels
|
| Debian 11 | Released |
28 kernels
|
| Debian 11 cloud | Released |
8 kernels
|
| Debian 12 | Planned | — |
| Proxmox VE 7 5.15 | Released |
43 kernels
|
| Ubuntu 16.04 AWS ESM | Will Not Fix | — |
| Ubuntu 16.04 AWS HWE ESM | Will Not Fix | — |
| Ubuntu 16.04 Azure ESM | Will Not Fix | — |
| Ubuntu 16.04 ESM | Will Not Fix | — |
| Ubuntu 16.04 GCP ESM | Will Not Fix | — |
| Ubuntu 16.04 HWE ESM | Will Not Fix | — |
| Ubuntu 18.04 | Planned | — |
| Ubuntu 18.04 AWS Focal | Released |
56 kernels
|
| Ubuntu 18.04 HWE Focal | Released |
69 kernels
|
| Ubuntu 20.04 | Released |
125 kernels
|
| Ubuntu 20.04 AWS | Released |
107 kernels
|
| Ubuntu 20.04 Azure | Released |
98 kernels
|
| Ubuntu 20.04 GCP | Ready For Release | — |
| Ubuntu 20.04 HWE AWS | Released |
37 kernels
|
| Ubuntu 20.04 HWE Azure | Released |
21 kernels
|
| Ubuntu 22.04 | Released |
50 kernels
|
| Ubuntu 22.04 AWS | Released |
44 kernels
|
| Ubuntu 22.04 Azure | Released |
41 kernels
|