nfc: llcp: fix OOB read and u8 offset wrap in TLV parsers

Overview

In the Linux kernel, the following vulnerability has been resolved:

nfc: llcp: fix OOB read and u8 offset wrap in TLV parsers

nfc_llcp_parse_gb_tlv() and nfc_llcp_parse_connection_tlv() contain three related bugs in their TLV parsing loops:

1. 'offset' is declared u8 but tlv_array_len is u16. When TLV data advances offset past 255 it silently wraps to zero, causing infinite loops or double-processing of buffer data.

2. Before reading tlv[0] (type) and tlv[1] (length) there is no check that offset+2 <= tlv_array_len. A truncated TLV causes an OOB read of one byte past the buffer end.

3. After reading the length field, the value bytes are accessed without checking offset+2+length <= tlv_array_len. A crafted length=0xFF on a short buffer causes up to 255 bytes of OOB read past the buffer end.

Both functions are reachable without authentication via nfc_llcp_set_remote_gb() which feeds remote LLCP general bytes directly into nfc_llcp_parse_gb_tlv() with no additional validation.

Fix all three issues by widening offset from u8 to u16 and adding bounds checks for both the TLV header and value field before each access.

Affected

• Linux >= 0be9de2ea01e8d52646e7310a7eef5459cf07ea8 < 2c1456fe09ab1a5a9fe1d8339ca6d509589b56e1
• Linux >= 3df40eb3a2ea58bf404a38f15a7a2768e4762cb0 < 7f6f3d087c67a4346189ef2c36481455bbc59a74
• Linux >= 3df40eb3a2ea58bf404a38f15a7a2768e4762cb0 < 9c47d667963542c3cf8e3007b7f10c0904d08238
• Linux >= 3df40eb3a2ea58bf404a38f15a7a2768e4762cb0 < a209334ed929941b20810c17c3a507445b0a7c85
• Linux >= 3df40eb3a2ea58bf404a38f15a7a2768e4762cb0 < 382eaa770335acf4f16a5a55524500f2bb4207df
• Linux >= 3df40eb3a2ea58bf404a38f15a7a2768e4762cb0 < 2d239590d1845a706304833d40dd6d4fec20ad88
• Linux >= 3df40eb3a2ea58bf404a38f15a7a2768e4762cb0 < e84cdfdc4a6c88e8b751144458f2e04e24415a28
• Linux >= 3df40eb3a2ea58bf404a38f15a7a2768e4762cb0 < 875285a165fd3b402de2ab3be0deb355d6f4caf5
• Linux >= 3df40eb3a2ea58bf404a38f15a7a2768e4762cb0 < 78b20c8eeacd2e44a2d8a4cb5316d3c521d90911
• Linux 1deacb5e031e289ca5636f2db4fcae6612c05d34
• Linux 66a1be74230bbe098e651766c9a0cf4038db8442
• Linux >= 5.10.188 < 5.10.267
• Linux >= 4.19.291 < 4.20
• Linux >= 5.4.251 < 5.5
• Linux 5.15

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.