SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2
In the Linux kernel, the following vulnerability has been resolved: SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2 gss_krb5_verify_mic_v2() reads the token ID at ptr[0..1], the flags byte at ptr[2], and padding at ptr[3..7], then passes ptr + GSS_KRB5_TOK_HDR_LEN and cksum_len to gss_krb5_mic_build_sg(). None of these accesses check read_token->len first. The minimum safe token size is GSS_KRB5_TOK_HDR_LEN (16) plus ctx->krb5e->cksum_len (12-24, depending on the enctype). All callers accept shorter tokens from the wire: - gss_unwrap_resp_integ() enforces only an upper bound (offset + len <= rcv_buf->len) before al