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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.
120 lines
2.9 KiB
C++
120 lines
2.9 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/HexInStream.h>
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#include <rdr/Exception.h>
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#include <stdlib.h>
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#include <ctype.h>
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using namespace rdr;
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const int DEFAULT_BUF_LEN = 16384;
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static inline int min(int a, int b) {return a<b ? a : b;}
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HexInStream::HexInStream(InStream& is, size_t bufSize_)
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: bufSize(bufSize_ ? bufSize_ : DEFAULT_BUF_LEN), offset(0), in_stream(is)
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{
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ptr = end = start = new U8[bufSize];
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}
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HexInStream::~HexInStream() {
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delete [] start;
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}
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bool HexInStream::readHexAndShift(char c, int* v) {
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c=tolower(c);
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if ((c >= '0') && (c <= '9'))
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*v = (*v << 4) + (c - '0');
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else if ((c >= 'a') && (c <= 'f'))
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*v = (*v << 4) + (c - 'a' + 10);
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else
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return false;
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return true;
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}
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bool HexInStream::hexStrToBin(const char* s, char** data, size_t* length) {
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size_t l=strlen(s);
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if ((l % 2) == 0) {
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delete [] *data;
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*data = 0; *length = 0;
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if (l == 0)
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return true;
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*data = new char[l/2];
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*length = l/2;
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for(size_t i=0;i<l;i+=2) {
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int byte = 0;
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if (!readHexAndShift(s[i], &byte) ||
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!readHexAndShift(s[i+1], &byte))
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goto decodeError;
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(*data)[i/2] = byte;
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}
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return true;
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}
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decodeError:
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delete [] *data;
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*data = 0;
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*length = 0;
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return false;
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}
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size_t HexInStream::pos() {
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return offset + ptr - start;
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}
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size_t HexInStream::overrun(size_t itemSize, size_t nItems, bool wait) {
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if (itemSize > bufSize)
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throw Exception("HexInStream overrun: max itemSize exceeded");
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if (end - ptr != 0)
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memmove(start, ptr, end - ptr);
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end -= ptr - start;
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offset += ptr - start;
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ptr = start;
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while ((size_t)(end - ptr) < itemSize) {
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size_t n = in_stream.check(2, 1, wait);
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if (n == 0) return 0;
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const U8* iptr = in_stream.getptr();
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const U8* eptr = in_stream.getend();
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size_t length = min((eptr - iptr)/2, start + bufSize - end);
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U8* optr = (U8*) end;
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for (size_t i=0; i<length; i++) {
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int v = 0;
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readHexAndShift(iptr[i*2], &v);
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readHexAndShift(iptr[i*2+1], &v);
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optr[i] = v;
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}
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in_stream.setptr(iptr + length*2);
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end += length;
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}
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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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