buffer overflow példa

buffover/Makefile

+#
+# Makefile a buffover eloallitasahoz
+#
+
+PROG = buffover
+SRCS = buffover.cpp secret.cpp
+HDRS = secret.h
+OBJS = $(SRCS:.cpp=.o)
+
+CXXFLAGS = -ggdb -Wall -Werror 
+
+$(PROG): $(OBJS) 
+	$(CXX) -o $(PROG) $(OBJS)
+
+.PHONY:
+clean:
+	rm -f $(OBJS) $(PROG)
+
+# Egyszerusites: Minden .o fugg minden header-tol, es meg a Makefile-tol is 
+$(OBJS): $(HDRS) Makefile
+
+

buffover/buffover.cbp

+<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
+<CodeBlocks_project_file>
+	<FileVersion major="1" minor="6" />
+	<Project>
+		<Option title="buffover" />
+		<Option pch_mode="2" />
+		<Option compiler="gcc" />
+		<Build>
+			<Target title="Debug">
+				<Option output="bin/Debug/buffover" prefix_auto="1" extension_auto="1" />
+				<Option object_output="obj/Debug/" />
+				<Option type="1" />
+				<Option compiler="gcc" />
+				<Compiler>
+					<Add option="-g" />
+				</Compiler>
+			</Target>
+			<Target title="Release">
+				<Option output="bin/Release/buffover" prefix_auto="1" extension_auto="1" />
+				<Option object_output="obj/Release/" />
+				<Option type="1" />
+				<Option compiler="gcc" />
+				<Compiler>
+					<Add option="-O2" />
+				</Compiler>
+				<Linker>
+					<Add option="-s" />
+				</Linker>
+			</Target>
+		</Build>
+		<Compiler>
+			<Add option="-Wall" />
+			<Add option="-fexceptions" />
+		</Compiler>
+		<Unit filename="buffover.cpp" />
+		<Unit filename="secret.cpp" />
+		<Unit filename="secret.h" />
+		<Extensions>
+			<DoxyBlocks>
+				<comment_style block="0" line="0" />
+				<doxyfile_project />
+				<doxyfile_build />
+				<doxyfile_warnings />
+				<doxyfile_output />
+				<doxyfile_dot />
+				<general />
+			</DoxyBlocks>
+			<code_completion />
+			<envvars />
+			<debugger />
+			<lib_finder disable_auto="1" />
+		</Extensions>
+	</Project>
+</CodeBlocks_project_file>

buffover/buffover.cpp

+/**
+ *  \file: buffover.cpp
+ *   (Latin-2 kodolasu fajl. Allitsa at a kodolast,
+ *    ha a tovabbi kommentek nem olvashatok helyesen!)
+ *
+ *  \brief Buffer overflow hiba bemutatsa
+ *
+ *  A helyes jelsz: titok
+ *  Prblja ki helyes s helytelen jelszval,
+ *  majd 7-10 bet hosszsg tetszleges jelszval is!
+ *
+ */
+
+#include <iostream>
+#include <cstring>
+#include "secret.h"
+
+using std::cin;
+using std::cout;
+using std::endl;
+
+char buff[6];
+bool pass = false;
+
+int main(void) {
+    initOutputEncoding();    // belltjuk a kdkszletet a kimeneten
+    cout << "Ha tudja a jelszt, megnzheti a ZH krdst!\n";
+    cout << "Jelszo: ";
+    cin >> buff;
+
+    if (strcmp(buff, "titok") != 0) {
+        cout << "*** Hibas jelszo ***" << endl;
+    } else {
+        cout << "Helyes jelszo" << endl;
+        pass = true;
+    }
+
+    if (pass) {
+        cout << ">> Hozzaferhet a titokhoz: <<" << endl;
+        printSecret();  // kirja a titkos informcit
+    }
+    return 0;
+}

buffover/secret.cpp

+/**
+ *  \file: secret.cpp
+ *   (Latin-2 kodolasu fajl. Allitsa at a kodolast,
+ *    ha a tovabbi kommentek nem olvashatok helyesen!)
+ *
+ *  \brief Pda az kezetes karakterek megjelentsre
+ *
+ *   UTF-8 kezelse bonyolultabb, mert 1 karakter tbb byte hossz is lehet.
+ *   LINUX-ban a LANG paranccsal be kell lltani a fjl kdolsnak
+ *   megfelel nyelvet (pl: LANG=hu_HU, vagy LANG=hu_HU.utf8
+ *
+ *   Ha tvoli termilemulcival csatlakozunk (pl. ssh, putty), akkor az
+ *   kezethelyes megjelenshez annak a kdkszlett is jl kell belltani.
+ *   (pl: putty -> change settings -> translation -> latin2)
+ *
+ *   Kdkonverzi: iconv (van Windows s Linux vltozata is)
+ */
+
+#include <iostream>
+#include <clocale>
+#define WINX defined(WIN32) || defined(_WIN32) || defined(WIN64) || defined(_WIN64)
+#if WINX
+#include <windows.h>
+#endif // WINX
+#include "secret.h"
+
+using std::cout;
+using std::endl;
+
+void printSecret() {
+    cout << "1. Mikor jelentkezik a buffer oveflow hiba?\n"
+         << "\ta) reggel\n"
+         << "\tb) aritmetikai tlcsordulskor\n"
+         << "\tc) ha elfogy a memria\n"
+         << "\td) egy vltozt (buffert) a program hosszabban r, mint annak a mrete" << std::endl;
+}
+
+void initOutputEncoding() {
+    setlocale(LC_ALL, "");
+#if WINX
+/// Windows alatt egyb varzslatra is szksg van ...
+    SetConsoleCP(1250);
+    SetConsoleOutputCP(1250);
+#endif
+}

buffover/secret.h

+#ifndef SECRET_H
+#define SECRET_H
+
+void printSecret();
+void initOutputEncoding();
+
+#endif // SECRET_H