Mitigation Strategies

The vulnerability is resolved by validating the skb length in RFCOMM MCC handlers in the Linux kernel. Immediate mitigation steps include updating the Linux kernel to a version where this fix is applied.

Specifically, the fix involves using skb_pull_data() to validate and access the required data before dereferencing it, preventing out-of-bounds reads caused by truncated MCC frames.

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Executive Summary

This vulnerability exists in the Linux kernel's Bluetooth RFCOMM MCC handlers. These handlers cast the skb->data pointer to protocol-specific structures without first validating the length of the skb (socket buffer). A malicious remote device can exploit this by sending truncated MCC frames, which causes the handlers to perform out-of-bounds reads of memory.

The issue is fixed by using skb_pull_data() to validate and safely access the required data before dereferencing it. Special handling is applied to the rfcomm_recv_rpn() function because the protocol allows 1-byte RPN requests, so it validates the DLCI byte first and the full structure only if the length is greater than one.

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Impact Analysis

This vulnerability can allow a malicious remote Bluetooth device to cause out-of-bounds memory reads in the Linux kernel's Bluetooth RFCOMM MCC handlers. Such out-of-bounds reads can potentially lead to information disclosure, system instability, or crashes, depending on how the kernel handles the invalid memory access.

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