Commit
bf883e0 ("MAJOR: session: implement a wait-queue for sessions who
need a buffer") introduced in 1.6 forgot to initialize the buffer_wait
list when the session is initiated by an applet for a peer, resulting in
a crash. Thanks to Chris Kopp for reporting the issue.
LIST_ADDQ(&sessions, &s->list);
LIST_INIT(&s->back_refs);
+ LIST_INIT(&s->buffer_wait);
s->flags = SN_ASSIGNED|SN_ADDR_SET;