Mitigation Strategies

The vulnerability has been resolved by bounding the UART receive buffer in the Linux kernel NFC pn533 driver. To mitigate this vulnerability, you should update your Linux kernel to a version that includes this fix, which drops accumulated partial frames once the fixed receive buffer is full, preventing malformed UART traffic from growing the buffer indefinitely.

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Executive Summary

This vulnerability exists in the Linux kernel's NFC pn533 driver, specifically in how it handles UART receive buffers.

The function pn532_receive_buf() appends every incoming byte to a buffer (recv_skb) and only resets this buffer when a complete PN532 frame is recognized.

If a continuous stream of bytes without a valid PN532 frame header is received, the buffer keeps growing until it reaches its tail limit, potentially causing issues.

The fix bounds the UART receive buffer by dropping the accumulated partial frame once the fixed receive buffer is full, preventing malformed UART traffic from growing the buffer beyond its limit.

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Impact Analysis

If exploited, this vulnerability could allow malformed UART traffic to cause the receive buffer to grow uncontrollably.

This could potentially lead to resource exhaustion or denial of service conditions in the NFC pn533 driver within the Linux kernel.

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