Wireshark-dev: Re: [Wireshark-dev] [Wireshark-commits] rev 40312: /trunk/ /trunk/epan/dissector
From: "Maynard, Chris" <[email protected]>
Date: Wed, 25 Jan 2012 15:23:01 -0500
> -----Original Message-----
> From: [email protected] [mailto:wireshark-dev-
> [email protected]] On Behalf Of Maynard, Chris
> Sent: Wednesday, December 28, 2011 12:21 PM
> To: '[email protected]'
> Subject: Re: [Wireshark-dev] [Wireshark-commits] rev 40312: /trunk/
> /trunk/epan/dissectors/: packet-bt-dht.c packet-gopher.c packet-
> gsm_ipa.c packet-meta.c packet-mux27010.c packet-nfs.c packet-rdp.c
> packet-sametime.c packet-ua.c packet-xtp.c ...
> 
> There are 2 other files that I believe also have tvb_get_string()-
> related memory leaks, but they are somewhat confusing to me, and so I
> would appreciate it if someone could take a look at them.
> 
> 1) packet-ldap.c:dissect_ldap_Mechanism(): 

I'm still not completely sure about this one if someone cares to have a look.

> 2) packet-wsp.c: At line 1281, there is a nice NOTE warning about
> ensuring to call g_free() since tvb_get_stringz() returns g_malloc()ed
> memory.  There is actually only 1 instance of tvb_get_stringz();
> however, it is called from the get_text_string() macro.
> get_text_string(), in turn, is called by a bunch of other macros, such
> as get_token_text(), get_extension_media(), get_text_value(),
> get_quoted_string(), get_uri_value() and get_version_value().  Because
> all of those therefore end up calling tvb_get_stringz(), I believe we
> need to see some g_free()'s after all of them.
> 
> This doesn't look like the case, but before I went to try to fix them,
> I noticed this confusing code/comment at line 2243:
>             get_token_text(val_str, tvb, off, len, ok); \
>             /* As we're using val_str, it is automatically g_free()d */
> \
> 
> There is no g_free() following that code, so I think there is a leak
> here and that the comment can't be true ... can it?  Am I missing
> something here?  I stopped looking for leaks at this point for this
> dissector until I can clear up this confusion.

Well, as far as I can tell, there must be leaks with the current implementation.  Attached are 2 different proposed patches to try to plug them.  The first one adds the g_free's where needed, and the second one just has get_text_string() return ep_alloc'd memory instead of g_malloc'd memory, so there's no need to have all the g_free's sprinkled all over the place anymore.  I prefer patch #2 as I think it's less error prone.  If no preference or problems with it, I'll commit that one soon ...

Thanks.
- Chris
P.S. Oh yes, maybe you could also take a look at the NOTE I added, as I don't understand why the call to get_uri_value() is made in that case.

> > -----Original Message-----
> > From: [email protected] [mailto:wireshark-
> > [email protected]] On Behalf Of [email protected]
> > Sent: Wednesday, December 28, 2011 11:37 AM
> > To: [email protected]
> > Subject: [Wireshark-commits] rev 40312: /trunk/
> > /trunk/epan/dissectors/: packet-bt-dht.c packet-gopher.c packet-
> > gsm_ipa.c packet-meta.c packet-mux27010.c packet-nfs.c packet-rdp.c
> > packet-sametime.c packet-ua.c packet-xtp.c ...
> >
> >
> http://anonsvn.wireshark.org/viewvc/viewvc.cgi?view=rev&revision=40312
> >
> > User: cmaynard
> > Date: 2011/12/28 08:36 AM
> >
> > Log:
> >  Fix memory leaks involving tvb_get_string[z]().
> >
> > Directory: /trunk/epan/dissectors/
> >   Changes    Path                 Action
> >   +5 -5      packet-bt-dht.c      Modified
> >   +1 -0      packet-gopher.c      Modified
> >   +1 -1      packet-gsm_ipa.c     Modified
> >   +3 -0      packet-meta.c        Modified
> >   +7 -5      packet-mux27010.c    Modified
> >   +3 -0      packet-nfs.c         Modified
> >   +6 -6      packet-rdp.c         Modified
> >   +1 -1      packet-sametime.c    Modified
> >   +4 -4      packet-ua.c          Modified
> >   +1 -0      packet-xtp.c         Modified
> >
> >
> > (1 file not shown)

-- 

Attachment: packet-wsp_2.patch
Description: packet-wsp_2.patch

Attachment: packet-wsp_1.patch
Description: packet-wsp_1.patch

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