CVE-2023-52456 serial: imx: fix tx statemachine deadlock
A deadlock in the Linux kernel's i.MX serial driver can render the RS485 interface unusable if the port is closed during transmission.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-52456?
CVE-2023-52456 is a medium-severity denial of service vulnerability in Linux kernel, published on 23 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
serial: imx: fix tx statemachine deadlock
When using the serial port as RS485 port, the tx statemachine is used to control the RTS pin to drive the RS485 transceiver TX_EN pin. When the TTY port is closed in the middle of a transmission (for instance during userland application crash), imx_uart_shutdown disables the interface and disables the Transmission Complete interrupt. afer that, imx_uart_stop_tx bails on an incomplete transmission, to be retriggered by the TC interrupt. This interrupt is disabled and therefore the tx statemachine never transitions out of SEND. The statemachine is in deadlock now, and the TX_EN remains low, making the interface useless.
imx_uart_stop_tx now checks for incomplete transmission AND whether TC interrupts are enabled before bailing to be retriggered. This makes sure the state machine handling is reached, and is properly set to WAIT_AFTER_SEND.
Weakness: CWE-667
Which versions are affected by CVE-2023-52456?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-52456?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2023-52456 being exploited?
There is no known exploitation of CVE-2023-52456 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-52456, DEBIAN-CVE-2023-52456, GHSA-53gx-3hrh-cr29, UBUNTU-CVE-2023-52456.