ng_tty: don't increment m_data

[vexeduxr]

Summary

Stop incrementing m_data so the callee can read the mbuf.

MFC after: 3 days

[kevans]

sys/netgraph/ng_tty.c

488

That would also imply that the previous code was pretty boken, right? This appends to mbuf at m->m_len, but *mtod(m, u_char *) = c is effectively m_data[0] = c rather than m_data[m_len++] = c

[kevans]

sys/netgraph/ng_tty.c

488

Oh, I guess if it's always incrementing m_data. sorry.

[vexeduxr]

sys/netgraph/ng_tty.c

488

Doing some more digging, this used to rely on setting m_data to m_pktdat before sending it off, but that seems to have been broken since 2ffded5

[glebius]

Thanks a lot for the fix and sorry for the breakage.

[vexeduxr]

No problem :)