[David Perry <boolean263@xxxxxxxxx>]

There are open issues for this already... sort of. #20431 reports that tshark will linearly but unboundedly consume memory when run with the -M option. #20432 is about CLI taps (not) freeing their memory properly, and wondering what the best approach is to remedy it.

20432 asks a larger design question about whether tshark should draw tap output and/or reset tap state when the session is reset. But since that question is academic while our CLI taps don't manage their memory, I've been working at adding/fixing reset and finish routines to most of our CLI taps, and pinging #20432 in each such MR.

I haven't done anything with the more complicated ones, such as tap-iousers.c that you named. Hopefully the work on the simpler taps will be useful for someone with a better understanding of the remainder.

Links:
<https://gitlab.com/wireshark/wireshark/-/issues/20431>
<https://gitlab.com/wireshark/wireshark/-/work_items/20432>

David

On 2025-06-28 21:31, Gilbert Ramirez wrote:

Correct, we don't want to free the allocation directly in the init function. Look at epan/tap.h for the documentation on register_tap_listener. The 2nd argument is "tapdata", or, the instance of the tap and all its state.

If you look at tap-rpcprogs.c, in rpcprogs_init(), you'll see a much clearer example.

The reason tap-iousers.c looks strange is that "&iu->hash" is passed as "tapdata".

*However*, the last argument to register_tap_listener() should be a "tap_finish" function which would free the memory, and that is missing!

I see some other taps in ui/cli that also forget to add a tap_finish callback. For example, tap-smbsids.c is also missing a tap_finish callback.

I guess no one noticed because these taps are instantiated a handful of times, at the most, during the running of tshark. So, it's a very minor oversight.

Would you like to open an issue at https://gitlab.com/wireshark/wireshark/-/issues/ to track this?

Gilbert

On Sat, Jun 14, 2025 at 11:52 AM Rustam Kovhaev via Wireshark-dev <wireshark-dev@xxxxxxxxxxxxx> wrote:

Hi,
First of all, thank you for Wireshark! I am using it a lot, and I mean
it, and I love it.
Quick sanity check, we don't free g_new0() allocation in init_iousers(),
do we?
This is harmless, just something I noticed while reading the code.
Thank you very much!
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