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s3: smbd: In reply_read_and_X() SMB1 server is overwriting part of the 'reserved' zero fields with reply data length.

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This occurred due to old code that used to do:

SSVAL(smb_buf(req->outbuf),-2,nread);

to set the reply length. This code was not needed,
as srv_set_message() was already correctly setting
the bcc length and was probably left from much
earlier legacy code.

However, in commit ddaa65ef6e
this was converted to do:

SSVAL(req->outbuf,smb_vwv11,smb_maxcnt);

This code actually overwrites the last 'reserved'
field in the SMB_COM_READ_ANDX packet reply, but we
never noticed as no client (or server code) looks at or
checks vwv11 in a SMB_COM_READ_ANDX reply.

[MS-SMB] shows for SMB_COM_READ_ANDX reply:

SMB_Parameters
{
        UCHAR WordCount;
        Words
        {
                UCHAR AndXCommand;
                UCHAR AndXReserved;
                USHORT AndXOffset;
                USHORT Available;
                USHORT DataCompactionMode;
                USHORT Reserved1;
                USHORT DataLength;
                USHORT DataOffset;
                USHORT DataLengthHigh;
                USHORT Reserved2[4];
        }
}
SMB_Data
{
        USHORT ByteCount;
        Bytes
        {
                UCHAR Pad[] (optional);
                UCHAR Data[variable];
        }

and indeed checking wireshark from Win2012R2
we find that smbd is writing the returned
read length into smb_vwv11 and Windows leaves
it as zeros (reserved).

Also fix the same problem in the named pipes code.

Torture test to ensure Reserved2[4] replies
are zero to follow.

https://bugzilla.samba.org/show_bug.cgi?id=11845

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Alexander Bokovoy <ab@samba.org>
This commit is contained in:
Jeremy Allison 2016-06-13 09:30:25 -07:00 committed by Alexander Bokovoy
parent 6507336d66
commit e57f9e15d0
2 changed files with 0 additions and 2 deletions
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1
source3/smbd/pipes.c
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@ -492,7 +492,6 @@ static void pipe_read_andx_done(struct tevent_req *subreq)
+ 12 * sizeof(uint16_t) /* vwv */ + 12 * sizeof(uint16_t) /* vwv */
+ 2 /* the buflen field */ + 2 /* the buflen field */
+ 1); /* padding byte */ + 1); /* padding byte */
SSVAL(req->outbuf,smb_vwv11,state->smb_maxcnt);
DEBUG(3,("readX-IPC min=%d max=%d nread=%d\n", DEBUG(3,("readX-IPC min=%d max=%d nread=%d\n",
state->smb_mincnt, state->smb_maxcnt, (int)nread)); state->smb_mincnt, state->smb_maxcnt, (int)nread));

1
source3/smbd/reply.c
View File

@ -3941,7 +3941,6 @@ int setup_readX_header(char *outbuf, size_t smb_maxcnt)
+ 2 /* the buflen field */ + 2 /* the buflen field */
+ 1); /* padding byte */ + 1); /* padding byte */
SSVAL(outbuf,smb_vwv7,(smb_maxcnt >> 16)); SSVAL(outbuf,smb_vwv7,(smb_maxcnt >> 16));
SSVAL(outbuf,smb_vwv11,smb_maxcnt);
SCVAL(smb_buf(outbuf), 0, 0); /* padding byte */ SCVAL(smb_buf(outbuf), 0, 0); /* padding byte */
/* Reset the outgoing length, set_message truncates at 0x1FFFF. */ /* Reset the outgoing length, set_message truncates at 0x1FFFF. */
_smb_setlen_large(outbuf, _smb_setlen_large(outbuf,