Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
can: netlink: can_changelink(): fix NULL pointer deref of struct can_priv::do_set_mode
Andrei Lalaev reported a NULL pointer deref when a CAN device is restarted from Bus Off and the driver does not implement the struct can_priv::do_set_mode callback.
There are 2 code path that call struct can_priv::do_set_mode:
- directly by a manual restart from the user space, via can_changelink()
- delayed automatic restart after bus off (deactivated by default)
To prevent the NULL pointer deference, refuse a manual restart or configure the automatic restart delay in can_changelink() and report the error via extack to user space.
As an additional safety measure let can_restart() return an error if can_priv::do_set_mode is not set instead of dereferencing it unchecked.
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 6 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 7 ELS , Oracle Linux 6 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- kernel @ 4.18.0 (+15 more)
In the Linux kernel, the following vulnerability has been resolved:
can: netlink: can_changelink(): fix NULL pointer deref of struct can_priv::do_set_mode
Andrei Lalaev reported a NULL pointer deref when a CAN device is restarted from Bus Off and the driver does not implement the struct can_priv::do_set_mode callback.
There are 2 code path that call struct can_priv::do_set_mode:
- directly by a manual restart from the user space, via can_changelink()
- delayed automatic restart after bus off (deactivated by default)
To prevent the NULL pointer deference, refuse a manual restart or configure the automatic restart delay in can_changelink() and report the error via extack to user space.
As an additional safety measure let can_restart() return an error if can_priv::do_set_mode is not set instead of dereferencing it unchecked.