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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.
88 lines
2.2 KiB
C++
88 lines
2.2 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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//
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// A MemOutStream grows as needed when data is written to it.
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//
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#ifndef __RDR_MEMOUTSTREAM_H__
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#define __RDR_MEMOUTSTREAM_H__
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#include <rdr/Exception.h>
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#include <rdr/OutStream.h>
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namespace rdr {
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class MemOutStream : public OutStream {
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public:
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MemOutStream(int len=1024) {
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start = ptr = new U8[len];
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end = start + len;
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}
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virtual ~MemOutStream() {
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delete [] start;
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}
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void writeBytes(const void* data, size_t length) {
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check(length);
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memcpy(ptr, data, length);
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ptr += length;
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}
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size_t length() { return ptr - start; }
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void clear() { ptr = start; };
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void clearAndZero() { memset(start, 0, ptr-start); clear(); }
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void reposition(size_t pos) { ptr = start + pos; }
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// data() returns a pointer to the buffer.
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const void* data() { return (const void*)start; }
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protected:
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// overrun() either doubles the buffer or adds enough space for nItems of
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// size itemSize bytes.
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size_t overrun(size_t itemSize, size_t nItems) {
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size_t len = ptr - start + itemSize * nItems;
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if (len < (size_t)(end - start) * 2)
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len = (end - start) * 2;
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if (len < (size_t)(end - start))
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throw Exception("Overflow in MemOutStream::overrun()");
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U8* newStart = new U8[len];
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memcpy(newStart, start, ptr - start);
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ptr = newStart + (ptr - start);
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delete [] start;
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start = newStart;
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end = newStart + len;
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return nItems;
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}
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U8* start;
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};
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}
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#endif
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