CVE-2023-52789 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
tty: vcc: Add check for kstrdup() in vcc_probe()
Add check for the return value of kstrdup() and return the error, if it fails in order to avoid NULL pointer dereference.
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Analysis
by VulDB Data Team • 05/27/2025
The vulnerability identified as CVE-2023-52789 resides within the Linux kernel's terminal multiplexer subsystem, specifically affecting the virtual console controller vcc module. This issue manifests as a potential null pointer dereference condition that could lead to system instability or denial of service. The vulnerability occurs during the probe phase of device initialization when the kernel attempts to duplicate a string using the kstrdup() function. The vcc_probe() function is responsible for initializing virtual console controller devices and establishing their communication channels within the terminal subsystem. When the kernel processes device enumeration and initialization for virtual console controllers, it relies on kstrdup() to create duplicate copies of string identifiers or configuration parameters that define the device characteristics and communication protocols.
The technical flaw stems from inadequate error handling within the vcc_probe() function where the return value of kstrdup() is not properly validated before subsequent operations. The kstrdup() function allocates memory and copies a string into the newly allocated space, but it can fail under memory pressure conditions or due to insufficient resources. When this allocation fails, kstrdup() returns a NULL pointer which, if not checked, gets passed to subsequent functions that expect valid string pointers. This failure to validate the kernel memory allocation result creates a path where a NULL pointer is dereferenced, potentially causing a kernel oops or system crash. The vulnerability is particularly concerning as it occurs during device initialization, meaning any device that triggers this code path during boot or hotplug operations could cause the entire system to become unstable. The error handling mechanism that should prevent such failures is missing or incomplete, allowing the kernel to continue execution with invalid data pointers.
The operational impact of this vulnerability extends beyond simple denial of service to potentially compromise system integrity and availability. When a virtual console controller device is probed and the kstrdup() allocation fails, the kernel continues processing without proper error propagation, leading to a cascade of potential failures. Attackers could potentially exploit this by triggering device enumeration with malformed parameters or by creating memory pressure conditions that force kstrdup() to fail. The vulnerability affects systems running Linux kernels where the vcc module is active, which typically includes embedded systems, server environments, and desktop systems that utilize virtual console controllers. The null pointer dereference could result in immediate system crashes, making the affected systems unreliable for critical operations. Additionally, since this occurs in kernel space, the impact could be more severe than user-space applications, potentially allowing for privilege escalation or information disclosure under certain conditions. The vulnerability aligns with CWE-476 which describes NULL pointer dereference issues, and represents a classic case of inadequate error handling in kernel code.
Mitigation strategies for CVE-2023-52789 focus on implementing proper error checking and return value validation in kernel code. The primary fix involves adding explicit checks for kstrdup() return values within the vcc_probe() function, ensuring that any NULL returns are properly handled and propagated back to the caller. This approach follows the principle of defensive programming and aligns with the ATT&CK framework's concept of privilege escalation through kernel vulnerabilities. System administrators should prioritize applying the relevant kernel patches that implement this check, as the vulnerability exists in the base kernel code and affects all systems running vulnerable kernel versions. The fix ensures that when memory allocation fails, the kernel properly returns an error code rather than continuing execution with invalid pointers. Organizations should also consider implementing memory monitoring and resource management strategies to reduce the likelihood of allocation failures that could trigger this vulnerability. The patch demonstrates the importance of proper error handling in kernel space where failures can have cascading effects on system stability and security. Regular kernel updates and vulnerability assessments remain crucial for maintaining system integrity, particularly in environments where virtual console controllers are actively used or where systems may be subject to resource exhaustion attacks.