CVE-2026-98288net: stmmac: fix TSO header length truncation

Official description

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix TSO header length truncation stmmac_tso_xmit() stores the protocol header length returned by stmmac_tso_header_size() in a u8. stmmac_tso_valid_packet() admits headers up to 1023 bytes, so a header longer than 255 bytes wraps modulo 256 (486 becomes 230, 256 becomes 0). A TCP over IPv6 socket carrying a few hundred bytes of sticky destination/hop-by-hop options makes skb_tcp_all_headers() exceed 255 while staying below the 1023-byte limit, so such an skb reaches stmmac_tso_xmit(). Widen proto_hdr_len to unsigned int, which is sufficient since the value is bounded by the hardware limit, and adjust the debug print specifier accordingly.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/bcf6013c2b4d732c6e4bf4d0f6ae4a18d63d414b
• https://git.kernel.org/stable/c/15989abd74f16f44bf953d056b95f1d2fda9b0cd