Re: se_alloc() GSList segfault woes

[Martin Mathieson <martin.r.mathieson () googlemail com>]

On Tue, Apr 20, 2010 at 4:57 PM, Martin Mathieson <
martin.r.mathieson () googlemail com> wrote:

> On Tue, Apr 20, 2010 at 4:45 PM, Jeff Morriss <jeff.morriss.ws () gmail com>wrote:
>
> > Jeremy O'Brien wrote:
> > > Hello everyone,
> > >
> > > I am using a static GSList to record some data about packets I've seen
> > > so that I can look up said info later. I've defined a custom callback
> > > for my g_slist_find_custom function that does NULL checking of the
> > > data that gets passed to it. I am allocating items that I append to
> > > the GSList with se_alloc(). The items are all very small. Essentially
> > > the problem is that wireshark segfaults whenever I open a capture file
> > > that uses this GSList, and then reopen it or another one that uses the
> > > GSList too. I believe I know why this is happening from my extraneous
> > > testing. It seems that the GSList (which gets created with the first
> > > call to g_slist_append()) sticks around after I open a new file, and
> > > my functions that add things to and search the list are crashing
> > > because they end up trying to access invalid memory (memory that was
> > > free'd do to my use of se_alloc for the items in the GSList). I feel
> > > that I could solve this by calling a g_slist_free() on my GSList (and
> > > set it to NULL) whenever my dissector opens a new file. I am not sure
> > > how to go about doing this however. I was trying to find a way to do
> > > the call on the first packet wireshark sees, so long as
> > > pinfo->fd->flags.visisted is not set, but I couldn't find a way to
> > > verify that this was the first packet dissected.
> >
> > The common solution is to call register_init_routine() to register a
> > routine that is called whenever the dissector should be reinitialized.
>
> You could take a look at address_hash_table is created and used in
> packet-arp.c.

Actually, thats not such a good example.  The key is the IP address, which
is just cast to a pointer.  The MAC address is in the looked-up value
instead...

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