Re: Crash in dissect_smb2_command

[Paul Offord <Paul.Offord () advance7 com>]

OK – I’ve added a comment to the change.

From: wireshark-dev-bounces () wireshark org [mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Jeff Morriss
Sent: 26 September 2016 14:53
To: Developer support list for Wireshark <wireshark-dev () wireshark org>
Subject: Re: [Wireshark-dev] Crash in dissect_smb2_command



On Sun, Sep 25, 2016 at 12:47 PM, Paul Offord <Paul.Offord () advance7 com<mailto:Paul.Offord () advance7 com>> wrote:
Hi,

Between 2.2 and the latest git a change seems to have been made to dissect_smb2_getinfo_request().  It now returns an 
integer based on the difference between two dissected values:

               offset = getinfo_offset + getinfo_size;

               return offset;

Unfortunately getinfo_offset and getinfo_size are sometimes zero and so a zero offset is returned.  On return to 
dissect_smb2_command there’s some fiddling around until we get to:

               proto_item_set_len(cmd_item, offset-old_offset);

The calculation of offset-old_offset yields a negative number which is passed to proto_item_set_len as a length 
parameter.  In proto_item_set_len we have:

               DISSECTOR_ASSERT(length >= 0);

Obviously this causes an exception.

Do I just feed this back as commentary on the Patch Set or should I raise a bug?

Either one works but if you do the former you should be prepared to remember the comment and raise a bug if you don't 
get a response.
If the former, can you point me to the change because I can’t seem to find it?

"git log -p" is your friend for this kind of thing (or "git blame"):

https://code.wireshark.org/review/17447

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