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Wireshark-bugs: [Wireshark-bugs] [Bug 9323] Buildbot crash output: fuzz-2013-10-25-12569.pcap

Date: Fri, 25 Oct 2013 16:48:02 +0000

Comment # 5 on bug 9323 from
(In reply to comment #4)
> (In reply to comment #3)
> > (In reply to comment #1)
> > > It appears the issue is that the format_text* functions in strutil.c have a
> > > small array of buffers that are used as a circular queue to store/return the
> > > "converted" string.  These are allocated on "first use", but since they're
> > > static variables in the function, are never freed.
> > > 
> > > Evan,
> > > Thoughts?
> > 
> > Not the issue in this bug? Asking valgrind for more information gives:
> 
> Still worthy of fixing?

Ya, though not a particularly high priority unless it's causing problems.
Probably all three should take a wmem scope as their first argument, and
allocate in that. That is the most flexible approach.

> > 
> > ==7729==  Uninitialised value was created by a heap allocation
> > ==7729==    at 0x4C2A2DB: malloc (in
> > /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
> > ==7729==    by 0x9551DC0: g_malloc (gmem.c:104)
> > ==7729==    by 0x4E3E223: buffer_init (buffer.c:35)
> > ==7729==    by 0x4E4693B: wtap_open_offline (file_access.c:551)
> > ==7729==    by 0x413693: cf_open (tshark.c:3853)
> > ==7729==    by 0x40AE2A: main (tshark.c:1930)
> > 
> > So I think this is probably at least a partial duplicate of bug #9292... I
> > will dig a little further.
> 
> I thought about that too after the fact, but at least this capture only has
> 1 frame, so hopefully the issue is easier to spot.

Ya, I *think* it's an abuse of tvb_get_ptr confused by the fact that wiretap
can overallocate packet buffers, so it turns into an "uninitialised value"
instead of the more logical "read past end of buffer".


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