CVE-2023-5563 in zephyr
Summary
by MITRE • 10/25/2023
The SJA1000 CAN controller driver backend automatically attempt to recover from a bus-off event when built with CONFIG_CAN_AUTO_BUS_OFF_RECOVERY=y. This results in calling k_sleep() in IRQ context, causing a fatal exception.
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Analysis
by VulDB Data Team • 10/31/2023
The SJA1000 CAN controller driver vulnerability represents a critical flaw in kernel-level device driver implementation that can lead to system crashes and potential security breaches. This vulnerability exists within the Linux kernel's CAN (Controller Area Network) subsystem where the SJA1000 controller driver automatically attempts to recover from bus-off events when the CONFIG_CAN_AUTO_BUS_OFF_RECOVERY kernel configuration option is enabled. The flaw manifests as an improper handling of interrupt context operations that violates fundamental kernel design principles and can result in immediate system termination.
The technical implementation of this vulnerability stems from the driver's automatic recovery mechanism attempting to invoke k_sleep() function within interrupt request context. This constitutes a direct violation of kernel execution model where blocking operations such as k_sleep() are strictly prohibited in interrupt handlers due to their potential to cause system deadlocks and undefined behavior. The k_sleep() function is designed for process context execution where the scheduler can safely put processes to sleep and resume them later, but when executed from interrupt context, it creates a fatal exception because the kernel cannot properly manage scheduling operations during interrupt processing. This specific flaw aligns with CWE-394 which addresses improper handling of interrupt contexts and improper use of kernel blocking functions in inappropriate execution contexts.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise vehicle safety systems and industrial control networks that rely on CAN bus communications. In automotive environments where the SJA1000 controller is commonly deployed, this vulnerability could result in complete loss of communication between vehicle control modules, leading to critical safety failures. The automatic recovery mechanism, intended to improve system reliability, becomes a liability when it triggers fatal exceptions during critical system operations. The vulnerability affects systems running Linux kernels with the specific configuration option enabled, making it particularly concerning for automotive, industrial, and embedded systems where CAN bus communication is fundamental to operation.
Mitigation strategies for this vulnerability require immediate kernel updates from vendors who have patched the specific driver implementation to prevent k_sleep() invocation from interrupt context. System administrators should disable the CONFIG_CAN_AUTO_BUS_OFF_RECOVERY configuration option if automatic recovery is not critical for their specific deployment. Organizations should implement comprehensive testing procedures to verify that CAN bus communication remains functional without automatic recovery mechanisms. The fix typically involves restructuring the driver code to perform bus-off recovery operations in process context rather than interrupt context, ensuring that blocking operations occur only when the kernel scheduler can properly manage execution flow. This vulnerability demonstrates the importance of adhering to kernel security best practices and following ATT&CK framework considerations for kernel-level exploits that target device driver implementations and interrupt handling mechanisms.