Bluetooth: hci_serdev: call init_rwsem() before p->open() in Kernel

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Background

The Kernel is a crucial component of the Linux operating system that provides core functionalities and acts as a bridge between hardware and software. It manages system resources, facilitates communication between different software components, and ensures the overall stability and security of the system. The hci_serdev module in the Kernel is responsible for handling Bluetooth communication over a serial device. It allows Bluetooth-enabled devices to connect and exchange data with the system. However, a vulnerability has been discovered in the hci_serdev module that could potentially be exploited by attackers.

Vulnerability Detail

The vulnerability in the hci_serdev module arises from a missing initialization of a read-write semaphore (init_rwsem) before calling the p->open() function. This oversight could lead to a race condition where multiple threads or processes attempt to access the same resource simultaneously, resulting in unexpected behavior or system crashes. An attacker could potentially exploit this vulnerability to gain unauthorized access to sensitive information, execute arbitrary code, or disrupt the normal functioning of the system. The vulnerability was introduced in version v4.16 of the Kernel and has been fixed in version v5.16.19.

Workaround

As a temporary workaround, users can disable the hci_serdev module by blacklisting it. This can be achieved by adding the following line to the /etc/modprobe.d/blacklist.conf file:

blacklist hci_serdev

After adding the line, the system needs to be rebooted for the changes to take effect. However, it is important to note that disabling the hci_serdev module will prevent Bluetooth functionality from working until the vulnerability is fixed.

Conclusion

In conclusion, the hci_serdev module in the Kernel is vulnerable to a race condition due to a missing initialization of a read-write semaphore. This vulnerability could be exploited by attackers to gain unauthorized access, execute arbitrary code, or disrupt the system. It is recommended to update the Kernel to version v5.16.19 or later to fix the vulnerability. Alternatively, users can disable the hci_serdev module as a temporary workaround. For further support and assistance in vulnerability remediation, please contact DevNack.com.

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