CVE-2023-54118 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
serial: sc16is7xx: setup GPIO controller later in probe
The GPIO controller component of the sc16is7xx driver is setup too early, which can result in a race condition where another device tries to utilise the GPIO lines before the sc16is7xx device has finished initialising.
This issue manifests itself as an Oops when the GPIO lines are configured:
Unable to handle kernel read from unreadable memory at virtual address ... pc : sc16is7xx_gpio_direction_output+0x68/0x108 [sc16is7xx]
lr : sc16is7xx_gpio_direction_output+0x4c/0x108 [sc16is7xx]
... Call trace: sc16is7xx_gpio_direction_output+0x68/0x108 [sc16is7xx]
gpiod_direction_output_raw_commit+0x64/0x318 gpiod_direction_output+0xb0/0x170 create_gpio_led+0xec/0x198 gpio_led_probe+0x16c/0x4f0 platform_drv_probe+0x5c/0xb0 really_probe+0xe8/0x448 driver_probe_device+0xe8/0x138 __device_attach_driver+0x94/0x118 bus_for_each_drv+0x8c/0xe0 __device_attach+0x100/0x1b8 device_initial_probe+0x28/0x38 bus_probe_device+0xa4/0xb0 deferred_probe_work_func+0x90/0xe0 process_one_work+0x1c4/0x480 worker_thread+0x54/0x430 kthread+0x138/0x150 ret_from_fork+0x10/0x1c
This patch moves the setup of the GPIO controller functions to later in the probe function, ensuring the sc16is7xx device has already finished initialising by the time other devices try to make use of the GPIO lines. The error handling has also been reordered to reflect the new initialisation order.
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Analysis
by VulDB Data Team • 01/03/2026
The vulnerability CVE-2023-54118 affects the Linux kernel's sc16is7xx serial driver implementation, specifically targeting the timing of GPIO controller initialization during device probe operations. This issue represents a classic race condition scenario where the driver's GPIO subsystem is initialized prematurely, creating a window of opportunity for concurrent access attempts from other kernel components. The vulnerability manifests as a kernel oops condition when GPIO lines are being configured, indicating an attempt to read from unreadable memory at virtual address locations. The root cause lies in the driver's initialization sequence where GPIO controller setup occurs before the primary device initialization is complete, violating fundamental kernel design principles for resource management and synchronization.
The technical flaw occurs within the sc16is7xx driver's probe function execution flow, where the GPIO controller component is established too early in the initialization process. This premature setup creates a race condition with other kernel subsystems that may attempt to utilize the same GPIO lines before the sc16is7xx device has fully completed its initialization sequence. The call trace demonstrates the execution path leading to the failure, showing that the error originates from sc16is7xx_gpio_direction_output function attempting to access memory locations that are not yet properly mapped or accessible. This represents a violation of the Linux kernel's memory management and device initialization protocols, where proper ordering of operations is critical to prevent undefined behavior and system instability.
The operational impact of this vulnerability extends beyond simple kernel oops conditions to potentially compromise system stability and reliability in embedded and industrial computing environments where the sc16is7xx serial devices are commonly deployed. When multiple devices or subsystems attempt to access GPIO lines simultaneously during the initialization phase, the kernel may experience unpredictable behavior including system crashes, data corruption, or complete system lockups. The vulnerability affects systems using the sc16is7xx family of serial communication controllers, which are widely employed in networking equipment, industrial automation systems, and embedded platforms where reliable GPIO functionality is essential for proper device operation and system integration.
The mitigation strategy implemented in the patch addresses this issue by reordering the initialization sequence within the driver's probe function, specifically moving the GPIO controller setup to occur after the primary device initialization has been completed. This modification ensures proper temporal ordering of operations and eliminates the race condition window that previously allowed concurrent access attempts to GPIO resources. The error handling logic has also been adjusted to align with the new initialization order, providing more robust failure recovery mechanisms. This fix aligns with established kernel development practices and security principles outlined in the Common Weakness Enumeration framework, specifically addressing CWE-362, which catalogs race conditions as a critical class of vulnerabilities in concurrent systems. The solution also reflects ATT&CK framework considerations for kernel-level vulnerabilities, particularly in the context of privilege escalation and system stability compromise through improper resource initialization sequences.