Operating systems form the backbone of the digital assets in any organization, and securing these systems is paramount. Recently, several vulnerabilities were identified in the Linux kernel, particularly concerning the Linux network drivers and USB support mechanisms. These vulnerabilities, known as CVE-2021-37159 and CVE-2021-46904, pose serious security risks if not addressed promptly.
The first of the vulnerabilities, CVE-2021-37159, was discovered in the Option USB High Speed Mobile device driver. It has been found that this driver does not properly handle error conditions, potentially allowing a physically proximate attacker to execute arbitrary code or cause a Denial of Service (DoS) attack via a system crash.
The core of the issue lies with the hso_free_net_device function in drivers/net/usb/hso.c, which calls unregister_netdev without checking if the device was actually in the NETREG_REGISTERED state. This could lead to a use-after-free scenario, severely compromising the system's stability and security.
The second vulnerability, CVE-2021-46904, concerns a null pointer dereference issue within the network drivers. This problem arises when multiple tty devices claim the same minor number, causing a double unregistration of the same device. The initial unregistration succeeds, but subsequent efforts result in a null pointer dereference.
The solution involved changes to the get_free_serial_index() function, which is now known as obtain_minor(). This revised function assigns a minor number immediately after one is found, preventing the reassignment of a minor number already in use. Correspondingly, set_serial_by_index() was renamed to release_minor() to better describe its functionality, ensuring that each obtain_minor() call has a corresponding release_minor() to free up the minor number.
These updates address significant risks and ensure a higher degree of system robustness, but they also underscore the need for ongoing vigilance and timely updates by system administrators. Companies deploying Linux systems should prioritize installing these updates to mitigate any potential security threats. Failing to do so could expose crucial systems to risks of manipulation and breakdown, which could be exploited by malicious entities.
In response to these findings, LinuxPatch has developed tailored solutions to assist customers in swiftly applying security patches to vulnerable systems. For more information on how to implement these crucial updates, please visit LinuxPatch.
By understanding these vulnerabilities and their implications, businesses using Linux can effectively guard against potential cyber attacks, maintaining their operational integrity and safeguarding sensitive data.