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https://github.com/kasmtech/KasmVNC.git
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ae6cbd19e9
We use a lot of lengths given to us over the network, so be more paranoid about them causing an overflow as otherwise an attacker might trick us in to overwriting other memory. This primarily affects the client which often gets lengths from the server, but there are also some scenarios where the server might theoretically be vulnerable. Issue found by Pavel Cheremushkin from Kaspersky Lab.
113 lines
2.6 KiB
C++
113 lines
2.6 KiB
C++
/* Copyright (C) 2002-2005 RealVNC Ltd. All Rights Reserved.
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*
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* This is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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* USA.
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*/
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#include <rdr/HexOutStream.h>
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#include <rdr/Exception.h>
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using namespace rdr;
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const int DEFAULT_BUF_LEN = 16384;
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static inline size_t min(size_t a, size_t b) {return a<b ? a : b;}
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HexOutStream::HexOutStream(OutStream& os, size_t buflen)
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: out_stream(os), offset(0), bufSize(buflen ? buflen : DEFAULT_BUF_LEN)
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{
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if (bufSize % 2)
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bufSize--;
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ptr = start = new U8[bufSize];
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end = start + bufSize;
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}
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HexOutStream::~HexOutStream() {
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delete [] start;
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}
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char HexOutStream::intToHex(int i) {
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if ((i>=0) && (i<=9))
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return '0'+i;
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else if ((i>=10) && (i<=15))
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return 'a'+(i-10);
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else
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throw rdr::Exception("intToHex failed");
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}
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char* HexOutStream::binToHexStr(const char* data, size_t length) {
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char* buffer = new char[length*2+1];
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for (size_t i=0; i<length; i++) {
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buffer[i*2] = intToHex((data[i] >> 4) & 15);
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buffer[i*2+1] = intToHex((data[i] & 15));
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if (!buffer[i*2] || !buffer[i*2+1]) {
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delete [] buffer;
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return 0;
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}
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}
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buffer[length*2] = 0;
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return buffer;
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}
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void
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HexOutStream::writeBuffer() {
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U8* pos = start;
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while (pos != ptr) {
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out_stream.check(2);
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U8* optr = out_stream.getptr();
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U8* oend = out_stream.getend();
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size_t length = min(ptr-pos, (oend-optr)/2);
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for (size_t i=0; i<length; i++) {
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optr[i*2] = intToHex((pos[i] >> 4) & 0xf);
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optr[i*2+1] = intToHex(pos[i] & 0xf);
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}
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out_stream.setptr(optr + length*2);
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pos += length;
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}
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offset += ptr - start;
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ptr = start;
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}
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size_t HexOutStream::length()
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{
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return offset + ptr - start;
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}
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void
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HexOutStream::flush() {
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writeBuffer();
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out_stream.flush();
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}
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size_t
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HexOutStream::overrun(size_t itemSize, size_t nItems) {
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if (itemSize > bufSize)
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throw Exception("HexOutStream overrun: max itemSize exceeded");
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writeBuffer();
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size_t nAvail;
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nAvail = (end - ptr) / itemSize;
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if (nAvail < nItems)
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return nAvail;
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return nItems;
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}
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