On Fri, Oct 30, 2020 at 9:33 AM Willem de Bruijn
[off-list ref] wrote:

Should this still check data[5] == FR_PAD?

No, the 6th byte (data[5]) is not a padding field. It is the first
byte of the SNAP header. The original code is misleading. That is part
of the reasons why I want to fix it with this patch.

The frame format is specified in RFC 2427
(https://tools.ietf.org/html/rfc2427). We can see in Section 4.1 and
4.2 that the 6th byte is the first byte of the SNAP header.