Hi,
Right now ep_ memory is freed at the begining of epan_dissect_run(),
which means that pointers allocated by ep_ can be safety accessed only before
dissecting next packet.
When using GUI epan_dissect_run() can be run when refreshing interface (think: packet list).
Which can happen at *any* time. Originally it caused bug #5284.
Right now we (I and Evan) can't reproduce this bug, but there's still the problem.
To make it reproductable (and clear) I want to make ep_ memory available
*only* when dissecting packet, i.e.
epan_dissect_run():
ep_free_all();
dissect_packet(edt, pseudo_header, data, fd, cinfo);
ep_free_all();
Taps also use ep_ memory, so I propose new function:
epan_dissect_run_tap():
ep_free_all();
tap_queue_init(edt);
dissect_packet(edt, pseudo_header, data, fd, cinfo);
tap_push_tapped_queue(edt);
ep_free_all();
(For now I want to have ep_free_all() before and after dissecting, before release we
can remove the one before).
Thanks to it, and memory scrubbing, any ep_ allocated pointer used after dissecting
should be catched fast.
It'll be no longer possible to save ep_ pointers in taps [1], or
communicate with UI by storing ep_ memory in packet_info.
I hope this proposal is understable and sane.
If we want to allow using ep_ memory between epan_dissect_init() and epan_dissect_cleanup()
we need more complicated allocator, which we currently don't have.
It's doable, but I'm not sure if really needed.
Regards,
Jakub.
[1] http://www.wireshark.org/lists/wireshark-dev/201210/msg00094.html
