Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
bonding: do not clear curr_active_slave prematurely when releasing all slaves
When releasing all slaves during bond destruction (all == true), __bond_release_one() unconditionally clears bond->curr_active_slave to NULL in every iteration.
If a backup slave is released before the active slave, bond_alb_deinit_slave() triggers rlb_teach_disabled_mac_on_primary(), which increments the active slave dev promiscuity counter and sets bond_info->primary_is_promisc = 1.
Because bond->curr_active_slave was prematurely cleared to NULL when releasing the backup slave, the subsequent iteration releasing the active slave evaluates oldcurrent as NULL, so bond_change_active_slave(bond, NULL) is skipped. Consequently, bond_alb_handle_active_change() is never called to decrement the promiscuity counter, permanently leaking promiscuous mode on the physical device after bond teardown.
When oldcurrent == slave, bond_change_active_slave(bond, NULL) already sets bond->curr_active_slave to NULL. We only need to avoid selecting a new active slave when all == true. Replace the if (all) branch with if (!all && oldcurrent == slave).
Details
- Affected product:
- AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 7 ELS , Debian 10 ELS , Debian 11 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 @ 5.4.0 (+17 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| Debian 12 | Planned | — |
| Debian 13 | Released |
17 kernels
|