Re: strange crash when a display filter is cleared on a reassembled packet

[Martin Kaiser <lists () kaiser cx>]

Hmm, no response...

I wasn't expecting people to spend time on reproducing this but I was
hoping that the backtrace would ring a bell for someone.

Yesterday, I played with DLNA traces and various wireshark versions
(down to 1.4.8). There's also been regular crashes when I cleared
display filters :-(

So I'm tempted to say it's unrelated to my DVB-CI code but it's
something particular for the FC15 box I'm running....

BTW another backtrace for the DVB-CI scenario described below is 

#0  0x41427f4a in IA__gtk_label_new (str=
    0x2e2e202e <Address 0x2e2e202e out of bounds>) at gtklabel.c:1398
#1  0x0809e68e in add_byte_tab (byte_nb=0x8cc2048 [GtkNotebook], name=
    0x2e2e202e <Address 0x2e2e202e out of bounds>, tvb=0x2e2e3030, tree=
    0xb7af1000, tree_view=0x8cb8208 [GtkTreeView]) at
main_proto_draw.c:708
#2  0x080a04a1 in add_byte_views (edt=0x8d66548, tree_view=
    0x8cb8208 [GtkTreeView], byte_nb_ptr=0x8cc2048 [GtkNotebook])
    at main_proto_draw.c:801
#3  0x080a04f1 in add_main_byte_views (edt=0x8d66548) at
main_proto_draw.c:779

in add_byte_views():

(gdb) print edt->pi.data_src
$7 = 0x8d3e720 = {0xb70f3000, 0xb70f301c, 0xb70f3038}
-> that's the Frame, reassembled TPDU and reassembled SPDU data sources

(gdb) print *(data_source *)0xb70f3000
$8 = {tvb = 0x8dcec90, name_initialized = 0, name = 0x14d40c7 "Frame"}
(gdb) print *(data_source *)0xb70f301c
$9 = {tvb = 0x2e2e3030, name_initialized = 774778400, name = 
    0x2e2e202e <Address 0x2e2e202e out of bounds>}
-> this one's content is invalid and still passed on to other routines,
   leading to a crash

Any idea how to shed some light on this?

Best regards,

   Martin

Thus wrote Martin Kaiser (lists () kaiser cx):

> Dear all,

> I'm struggling with a strange crash, I'd really appreciate your help.

> It may be that my DVB-CI dissector, other parts of wireshark or my
> system configuration is at fault...

> current svn on a Fedora Core 15 linux
> TShark 1.7.0 (SVN Rev Unknown from unknown)

> Copyright 1998-2011 Gerald Combs <gerald () wireshark org> and
> contributors.  This is free software; see the source for copying
> conditions. There is NO warranty; not even for MERCHANTABILITY or
> FITNESS FOR A PARTICULAR PURPOSE.
> Compiled (32-bit) with GLib 2.28.8, with libpcap 1.1.1, with libz 1.2.5,
> with POSIX capabilities (Linux), with threads support, without libpcre,
> without SMI, without c-ares, without ADNS, without Lua, with Python
> 2.7.1, with GnuTLS 2.10.5, with Gcrypt 1.4.6, with MIT Kerberos, without
> GeoIP.
> Running on Linux 2.6.40-4.fc15.i686.PAE, with locale en_US.UTF-8, with
> libpcap version 1.1.1, with libz 1.2.5.
> Built using gcc 4.6.0 20110603 (Red Hat 4.6.0-10).


> The problem can be reproduced by setting a display filter to
> dvb-ci.apdu_tag
> so that only APDUs are displayed

> Next, load http://www.kaiser.cx/misc/crash5.pcap, select packet 53
> (Profile Information) and click on Clear to clear the display filter

> This causes a segfault, backtrace is

> #0  ensure_contiguous_no_exception (tvb=0xcb5af808, offset=0, length=-1, 
>     exception=0xbfffd4dc) at tvbuff.c:852
> #1  0x0072e2c3 in ensure_contiguous (tvb=<optimized out>, 
>     offset=<optimized out>, length=-1) at tvbuff.c:887
> #2  0x080a01f9 in get_byte_view_data_and_length (byte_view=
>     0x8cc62f8 [GtkTextView], data_len=0xbfffd53c) at


> Packet 53 is reassembled on both session and transport layer
> There are 3 data sources: Frame (13 Bytes), reassembled tpdu (35 bytes),
> reassembled spdu (128 bytes).

> Setting a breakpoint in ensure_contiguous_no_exception() before pressing
> the clear button shows the following


> -> the Frame (13 bytes)
> (gdb) print *tvb
> $12 = {type = TVBUFF_REAL_DATA, initialized = 1, usage_count = 2, ds_tvb = 0x8dd6cc8, used_in = 0x8dc5708 = 
> {0x8dd6c20}, tvbuffs = {subset = {tvb = 0xffff, offset = 1710618, length = 437918234}, composite = {tvbs = 0xffff = 
> {<error reading variable>}, real_data = 0x822581c "", length = 13, reported_length = 13, raw_offset = 0, free_cb = 0}
> (gdb) cont 
> Continuing.

> -> Reassembled TPDU (35 Bytes)
> Breakpoint 2, ensure_contiguous_no_exception (tvb=0x8dd6c58, offset=0,
> length= -1, exception=0xbfffd4dc) at tvbuff.c:849 849     {
> (gdb) print *tvb
> $13 = {type = TVBUFF_REAL_DATA, initialized = 1, usage_count = 2, ds_tvb = 0x8dd6c58, used_in = 0x8dbc018 = 
> {0x8ddde78}, tvbuffs = {subset = {tvb = 0xffff, offset = 1710618, length = 437918234}, composite = {tvbs = 0xffff = 
> {<error reading variable>}, real_data = 0x8cd0aa8 " !\001", 'ÿ' <repeats 32 times>, length = 35, reported_length = 
> 35, raw_offset = 0, free_cb = 0}

> -> next, ensure_contiguous_no_exception() is called with an illegal
> address as tvb *

> Breakpoint 2, ensure_contiguous_no_exception (tvb=0xb7e82720, offset=0,
> length= -1, exception=0xbfffd4dc) at tvbuff.c:849 849     {
> (gdb) print *tvb
> $14 = {type = 16927523, initialized = 16927530, usage_count = 16927537, ds_tvb = 0x1024b38, used_in = 0x1024b3f = 
> {0x14244489, <error reading variable>

> (on some occassions, the tvb address was not accessible at all)

> continue -> segfault when the illegal pointer is dereferenced

> The crash only happens when a display filter is set before the capture
> file is loaded.

> I was not able to reproduce the crash on Debian Lenny.

> Wireshark doesn't crash if I delete the last packet (number 65) from the
> pcap file. It also doesn't crash if any other file is loaded before
> loading crash5.pcap.

> Any idea what's going wrong or what I can do to track this down?
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