Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
net/rds: No shortcut out of RDS_CONN_ERROR
RDS connections carry a state “rds_conn_path::cp_state” and transitions from one state to another and are conditional upon an expected state: “rds_conn_path_transition.”
There is one exception to this conditionality, which is “RDS_CONN_ERROR” that can be enforced by “rds_conn_path_drop” regardless of what state the condition is currently in.
But as soon as a connection enters state “RDS_CONN_ERROR”, the connection handling code expects it to go through the shutdown-path.
The RDS/TCP multipath changes added a shortcut out of “RDS_CONN_ERROR” straight back to “RDS_CONN_CONNECTING” via “rds_tcp_accept_one_path” (e.g. after “rds_tcp_state_change”).
A subsequent “rds_tcp_reset_callbacks” can then transition the state to “RDS_CONN_RESETTING” with a shutdown-worker queued.
That’ll trip up “rds_conn_init_shutdown”, which was never adjusted to handle “RDS_CONN_RESETTING” and subsequently drops the connection with the dreaded “DR_INV_CONN_STATE”, which leaves “RDS_SHUTDOWN_WORK_QUEUED” on forever.
So we do two things here:
a) Don’t shortcut “RDS_CONN_ERROR”, but take the longer path through the shutdown code.
b) Add “RDS_CONN_RESETTING” to the expected states in “rds_conn_init_shutdown” so that we won’t error out and get stuck, if we ever hit weird state transitions like this again."
Details
- Affected product:
- AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Debian 10 ELS , Oracle Linux 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- linux-meta @ 5.4.0 (+11 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| Amazon Linux 2023 | Planned | — |
| Debian 11 | Released |
37 kernels
|
| Debian 11 cloud | Released |
17 kernels
|
| Debian 13 | Planned | — |
| 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 |
97 kernels
|
| Ubuntu 22.04 AWS | Released |
88 kernels
|
| Ubuntu 22.04 Azure | Released |
78 kernels
|
| Ubuntu 24.04 | Released |
45 kernels
|
| Ubuntu 24.04 AWS | Planned | — |