Bluetooth Serialization Flaw in Linux Kernel

Executive Summary

This vulnerability exists in the Linux kernel's Bluetooth subsystem. Specifically, the function bt_sock_poll() accesses the accept queue without proper synchronization. During this unsynchronized access, a child socket can be removed and its last reference dropped, leading to potential issues. The vulnerability has existed since the initial Bluetooth import into the kernel.

The fix involves protecting the accept queue (accept_q) with a dedicated lock to ensure safe updates and polling. Additionally, the bt_accept_dequeue() function was reworked to take temporary references to child sockets under the queue lock before releasing it and locking the child socket.

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Mitigation Strategies

The vulnerability in the Linux kernel Bluetooth subsystem involves unsynchronized access to the accept queue. To mitigate this vulnerability, ensure your Linux kernel is updated to a version where this issue has been resolved.

• Update the Linux kernel to the latest version that includes the fix for serializing accept_q access.
• Apply any vendor-provided patches or security updates related to Bluetooth socket handling.
• Restart Bluetooth services or the system after applying updates to ensure the fix is active.

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Impact Analysis

This vulnerability in the Linux kernel Bluetooth subsystem involves unsynchronized access to the accept queue, which can lead to race conditions when sockets are accepted or torn down. This could potentially cause instability or unexpected behavior in Bluetooth connections, such as dropped connections or resource leaks.

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