Wireshark-bugs: [Wireshark-bugs] [Bug 5954] New: Assert in 6LoWPAN Dissector when opening corrup
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5954
Summary: Assert in 6LoWPAN Dissector when opening corrupt FRAG1
Packet
Product: Wireshark
Version: SVN
Platform: All
OS/Version: All
Status: NEW
Severity: Minor
Priority: Low
Component: Wireshark
AssignedTo: wireshark-bugs@xxxxxxxxxxxxx
ReportedBy: coflynn@xxxxxxxxx
Created an attachment (id=6392)
--> (https://bugs.wireshark.org/bugzilla/attachment.cgi?id=6392)
Example which triggers the assert
Build Information:
TShark 1.7.0 (SVN Rev 37390 from /trunk)
Copyright 1998-2011 Gerald Combs <gerald@xxxxxxxxxxxxx> 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 (64-bit) with GLib 2.26.0, with libpcap 1.1.1, with libz 1.2.5, with
POSIX capabilities (Linux), without libpcre, without SMI, without c-ares,
without ADNS, without Lua, without Python, with GnuTLS 2.8.6, with Gcrypt
1.4.5,
with MIT Kerberos, without GeoIP.
Running on Linux 2.6.35.11-83.fc14.x86_64, with libpcap version 1.1.1, with
libz
1.2.5.
Built using gcc 4.5.1 20100924 (Red Hat 4.5.1-4).
--
Opening a corrupt 6LoWPAN packet may trigger a dissector bug, with the
following error:
** (process:15471): WARNING **: Dissector bug, protocol 6LoWPAN, in packet 1:
tvbuff.c:633: failed assertion "tvb && tvb->initialized"
The reason is around line 2023 of packet-6lowpan.c. There are a number of calls
to dissect_6lowpan_xxx() which return a 'tvb' type. If the calls fail the tvb
is NULL, but that condition is never checked.
Attached file fixes that by introducing a simple check:
/* Check call to dissect_6lowpan_xxx was successful */
if (frag_tvb == NULL) {
return NULL;
}
The sub-dissectors which were called should print expert info messages when
they return NULL, so I don't think any additional expert info message is
required when we fail here.
--
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