Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
net_sched: red: fix a race in __red_change()
Gerrard Tai reported a race condition in RED, whenever SFQ perturb timer fires at the wrong time.
The race is as follows:
CPU 0 CPU 1 [1]: lock root [2]: qdisc_tree_flush_backlog() [3]: unlock root | | [5]: lock root | [6]: rehash | [7]: qdisc_tree_reduce_backlog() | [4]: qdisc_put()
This can be abused to underflow a parent’s qlen.
Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog() should fix the race, because all packets will be purged from the qdisc before releasing the lock.
Details
- Affected product:
- AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Oracle Linux 7 ELS , TuxCare 9.6 ESU , Ubuntu 20.04 ELS
- Affected packages:
- kernel @ 5.14.0 (+7 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| AlmaLinux 9.2 ESU | Released |
14 kernels
|
| AlmaLinux 9.6 ESU | Released |
1 kernel
|
| Amazon Linux 2023 | Planned | — |
| Debian 11 | Released |
35 kernels
|
| Debian 11 cloud | Released |
15 kernels
|
| Debian 12 | Released |
28 kernels
|
| Oracle Linux 7 UEK 6 | Released |
112 kernels
|
| Oracle Linux 8 UEK 6 | Released |
129 kernels
|
| Oracle Linux 8 UEK 7 | Released |
70 kernels
|
| Oracle Linux 9 UEK 7 | Released |
70 kernels
|
| Proxmox VE 7 5.15 | Released |
47 kernels
|
| Ubuntu 20.04 HWE AWS | Released |
57 kernels
|
| Ubuntu 20.04 HWE Azure | Released |
40 kernels
|
| Ubuntu 22.04 | Released |
81 kernels
|
| Ubuntu 22.04 AWS | Released |
72 kernels
|
| Ubuntu 22.04 Azure | Released |
66 kernels
|
| Ubuntu 24.04 | Released |
37 kernels
|