Re: issue: SMB2: The value of "Fixed Part Length" seems wrong

[Alexis La Goutte <alexis.lagoutte () gmail com>]

Hi Zhai,

Can you open a issue on bug tracker and a pcap ? https://bugs.wireshark.org

You can also push a fix directly on Gerrit https://code.wireshark.org/review
and look for help https://wiki.wireshark.org/Development/SubmittingPatches

Cheers

On Tue, Sep 24, 2019 at 1:06 PM Xuan k <kxuanobj () gmail com> wrote:

> Hi everyone,
>
> I found a issue about SMB2 protocol. The wireshark gives a wrong value on
> "Fixed Part Length" field.
>
> This is a Close Request message:
> Close Request (0x06)
>   StructureSize: 0x0018
>     0000 0000 0001 100. = Fixed Part Length: 12
>     .... .... .... ...0 = Dynamic Part: False
>   Close Flags: 0x0000
>   GUID handle File: Templates
>
> But the "Fixed Part Length" should be 24 in this message, not 12.
>
> It seems that the problem is caused by misusing the bit mask of
> struct header_field_info.
> The source line epan/dissectors/packet-smb2.c:10984 use a mask 0xFFFE to
> filter out the field.
> 10982                 { &hf_smb2_buffer_code_len,
> 10983                         { "Fixed Part Length",
> "smb2.buffer_code.length", FT_UINT16, BASE_DEC,
> 10984                         NULL, 0xFFFE, "Length of fixed portion of
> PDU", HFILL }
> 10985                 },
>
> But in function `proto_tree_set_uint` (epan/proto.c:5281), it shifts the
> numberic, and cause the numberic been divided by 2.
>
> hope this issue will be resolved soon.
>
> Thanks,
> Zhai Zhaoxuan
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