{"id":615,"date":"2012-06-15T20:28:26","date_gmt":"2012-06-15T12:28:26","guid":{"rendered":"http:\/\/www.dogeye.net\/?p=615"},"modified":"2012-06-15T20:28:26","modified_gmt":"2012-06-15T12:28:26","slug":"c%e8%af%ad%e8%a8%80%e5%92%8c%e5%ae%83%e7%9a%84%e5%ae%89%e5%85%a8%e6%80%a7","status":"publish","type":"post","link":"https:\/\/ykyi.net\/?p=615","title":{"rendered":"C\u8bed\u8a00\u548c\u5b83\u7684\u5b89\u5168\u6027"},"content":{"rendered":"<p>\u539f\u6587:&nbsp;<a href=\"http:\/\/avikivity.blogspot.com\/2011\/08\/c-assembly-and-security.html\" target=\"_blank\" rel=\"noopener\">http:\/\/avikivity.blogspot.com\/2011\/08\/c-assembly-and-security.html<\/a><\/p>\n<p>ykyi.net \u7ffb\u8bd1\u3002<\/p>\n<p>\u6211\u4eec\u770b\u4e0b\u9762\u4e00\u4e2aC\u8bed\u8a00\u7684\u53e5\u5b50\uff1a<\/p>\n<p>a = b + c<\/p>\n<p>\u4ec0\u4e48\u65f6\u5019\u8fd9\u4e2a\u53e5\u5b50\u4f1a\u9020\u6210\u9519\u8bef\u5462\uff1f<\/p>\n<p>1. a, b, c \u4e0d\u662f\u6211\u4eec\u60f3\u8981\u7684\u503c\u3002\u4e5f\u5c31\u662f\u6211\u4eec\u628a\u53d8\u91cf\u540d\u5199\u9519\u4e86\u3002<\/p>\n<p>2. \u5199\u4e86\u52a0\u6cd5\uff0c\u4f46\u662f\u6211\u4eec\u8981\u7684\u4e0d\u662f\u52a0\u6cd5\u3002<\/p>\n<p>3. \u505a\u4e86\u52a0\u6cd5\u540e\u503c\u6ea2\u51fa\u4e86\u3002<\/p>\n<p>4. a\u548cb\u662f\u65e0\u7b26\u53f7\u7c7b\u578b\uff0c\u800cc\u5374\u662f\u6709\u7b26\u53f7\u7c7b\u578b\u5e76\u4e14\u662f\u8d1f\u6570\uff0cb+c\u540e\u5f97\u5230\u8d1f\u6570\u53c8\u8d4b\u7ed9a.<\/p>\n<p>5. sizeof(a)\u6bd4sizeof(b)\u548csizeof(c)\u8981\u5c0f\u3002\u53c8\u6ea2\u51fa\u4e86\uff01<\/p>\n<p>6. a\u662f\u6709\u7b26\u53f7\u578b\uff0cb\u548cc\u662f\u65e0\u7b26\u53f7\u578b\u3002b+c\u540e\u8d4b\u7ed9a\uff0c\u6ea2\u51fa\u540e\uff0ca\u53d8\u6210\u8d1f\u503c\u3002<\/p>\n<p>7. a\u662f\u65e0\u7b26\u53f7\u578b\uff0cb\u548cc\u662f\u6709\u7b26\u53f7\u578b\uff1b\u518d\u6b21\u6ea2\u51fa\u3002<\/p>\n<p>\u6211\u4eec\u4e0d\u80fd\u671f\u671bC\u8bed\u8a00\u672c\u8eab\u80fd\u907f\u514d\u6240\u6709\u8fd9\u4e9b\u9519\u8bef\uff0c\u4f46\u6211\u4eec\u53ef\u4e0d\u53ef\u4ee5\u901a\u8fc7\u5728\u8fd0\u884c\u65f6Trap\u4e0a\u8ff0\u7684\u4e00\u4e9b\u9519\u8bef\u6539\u8fdbC\u8bed\u8a00\u4f7f\u4e4b\u66f4\u5b89\u5168\u5462\uff1f\u7ed3\u679c\u65f6\uff0c\u9664\u975e\u727a\u7272\u6027\u80fd\uff0c\u5426\u5219\u505a\u4e0d\u5230\u3002\u4f46\u6211\u4eec\u80fd\u727a\u7272\u6027\u80fd\u5417\uff1f<\/p>\n<p>&nbsp;<\/p>\n<p>&diams; \u4e3a\u4e86\u5904\u7406\u7b2c(3)\u79cd\u60c5\u51b5\uff0c\u6211\u4eec\u9700\u8981Trap\u6240\u4ee5\u6709\u7b26\u53f7\u6570\u7684\u52a0\u6cd5\u548c\u6240\u4ee5\u65e0\u7b26\u53f7\u6570\u7684\u52a0\u6cd5\u6307\u4ee4\u3002<\/p>\n<p>&diams; \u4e3a\u4e86\u5904\u7406\u7b2c(4)\u79cd\u60c5\u51b5\uff0c\u9700\u8981\u4e00\u4e2a\u6df7\u6742\u6709\u7b26\u53f7\u548c\u65e0\u7b26\u53f7\u7684\u52a0\u6cd5\u6307\u4ee4\u88abTrap\u3002<\/p>\n<p>&diams; \u4e3a\u4e86\u5904\u7406\u7b2c(5)\u79cd\u60c5\u51b5\uff0c\u9700\u8981Trap\u5b58\u50a8\u6709\u7b26\u53f7\u6570\u548c\u65e0\u7b26\u53f7\u6570\u7684\u6307\u4ee4\u3002\u5728Trap\u4e2d\u68c0\u67e5\u5bc4\u5b58\u5668\u4e2d\u7684\u503c\u4e0e\u5b58\u5165\u7684\u5185\u5b58\u5730\u5740\u662f\u5426\u5339\u914d\u3002<\/p>\n<p>&diams; (6)\u548c(7)\u4e0e\u4e0a\u7c7b\u4f3c\u3002<\/p>\n<p>&nbsp;<\/p>\n<p>\u8fd9\u4e9b\u770b\u4f3c\u7b80\u5355\u7684\u95ee\u9898\u5728\u5b89\u5168\uff0c\u6f0f\u6d1e\u65b9\u9762\u7ecf\u5e38\u51fa\u73b0\u3002\u6211\u4eec\u5f88\u96be\u53d1\u73b0\u5e76\u4fee\u590d\u8fd9\u4e9b\u95ee\u9898\uff0c\u56e0\u4e3a\u6ca1\u6709\u6240\u9700\u8981\u7684\u5904\u7406\u5668\u6307\u4ee4\u3002\u5f53\u7136\u6211\u4eec\u53ef\u4ee5\u7528\u5df2\u7ecf\u5b58\u5728\u7684\u6307\u4ee4\u6a21\u62df\u5b83\u4eec\u3002\u4f46\u662f\u8fd9\u6837\u505a\u80af\u5b9a\u4f1a\u635f\u5bb3\u6027\u80fd\u5e76\u4e14\u4f7f\u7a0b\u5e8f\u7684\u4f53\u79ef\u589e\u5927\u3002\u56e0\u4e3a\u7a0b\u5e8f\u6027\u80fd\u662f\u53ef\u4ee5\u88ab\u5ea6\u91cf\u7684\uff0c\u800c\u5ea6\u91cf\u5b89\u5168\u95ee\u9898\u5219\u6bd4\u8f83\u56f0\u96be\u3002\u7ed3\u679c\u65f6\u7559\u4e0b\u4e86\u5f88\u591a\u5145\u6ee1\u6f0f\u6d1e\u7684\u4ee3\u7801(exploitable code)\u3002<\/p>\n<p>\u4e0d\u7981\u8981\u95ee\uff0c\u4e3a\u4ec0\u4e48\u6211\u4eec\u6ca1\u6709\u8fd9\u4e9b\u6307\u4ee4\u5462\uff1f\u5728\u4e0a\u4e16\u7eaa\u7684\u4e03\uff0c\u516b\u5341\u5e74\u4ee3\uff0c\u6b63\u5728\u5feb\u901f\u6210\u957f\u7684\u8ba1\u7b97\u673a\u5de5\u4e1a\u754c\u9762\u4e34\u7684\u6700\u5927\u95ee\u9898\u662f\u6027\u80fd\uff0c\u800c\u4e0d\u662f\u5b89\u5168\u3002\u90a3\u65f6\u7684\u4ee3\u7801\u91cf\u5f88\u5c0f\uff0c\u4e5f\u5f88\u5bb9\u6613\u505a\u68c0\u67e5\uff1b\u7f51\u7edc\u8fd8\u5728\u6700\u521d\u7ea7\u7684\u9636\u6bb5\uff0c\u5f88\u5c0f\uff0c\u800c\u4e14\u57fa\u672c\u4e0a\u662f\u79c1\u6709\u7684\uff1b\u57fa\u672c\u4e0d\u5b58\u5728\u6076\u610f\u7684\u653b\u51fb\u3002<\/p>\n<p>C\u8bed\u8a00\u5728\u5f53\u65f6\u7684\u4f5c\u6cd5\u662f\u4e3a\u4e86\u80fd\u591f\u5728\u9002\u5408\u5f53\u65f6\u6240\u6709\u7684\u5904\u7406\u5668\uff0c\u56e0\u6b64C\u8bed\u8a00\u7684\u8bed\u4e49\u6a21\u4eff\u5f53\u65f6\u7684\u5904\u7406\u5668\u6307\u4ee4\u96c6\u3002\u4e4b\u540e\uff0cC\u8bed\u8a00\u5927\u83b7\u6210\u529f\uff0c\u5927\u91cf\u7684\u5904\u7406\u5668\u5219\u9488\u5bf9C\u8bed\u8a00\u505a\u4f18\u5316\uff0c\u5f88\u591a\u6307\u4ee4\u76f4\u63a5\u9488\u5bf9C\u8bed\u8a00\u7684\u8bed\u4e49\u505a\u4f18\u5316\u6216\u53ef\u4ee5\u76f4\u63a5\u5bf9\u5e94\u5230C\u8bed\u8a00\u7684\u8bed\u4e49\u3002\u8fd9\u6837\uff0c\u4f7f\u5f97C\u8bed\u8a00\u66f4\u52a0\u6d41\u884c\u4e86\u3002<\/p>\n<p>X86\u7684\u4e16\u754c\u91cc\u6709\u4e24\u4e2a\u6307\u4ee4: INTO\u548cBOUND\u662f\u6781\u597d\u7684\u4f8b\u5b50\u3002INTO(INTerrupt on Overflow)\u53ef\u4ee5\u5728\u4e00\u4e2a\u52a0\u6cd5\u6307\u4ee4\u6216\u8005\u51cf\u6cd5\u6307\u4ee4\u4e4b\u540e\u3002INTO\u53ef\u4ee5\u7528\u6765\u4f5c\u4e3a\u4e0a\u6587\u6307\u5230\u8fc7\u7684Trap\u6709\u7b26\u53f7\u52a0\u51cf\u6cd5\u7684\u6307\u4ee4\u3002BOUND\u5219\u5bf9\u6570\u7ec4\u64cd\u4f5c\u662f\u5426\u8d8a\u754c\u505a\u68c0\u67e5\u3002\u4f46\u662fBOUND\u6781\u5c11\u88ab\u4f7f\u7528\u3002\u6700\u540e\uff0c\u5728x86\u4f53\u7cfb\u8fc7\u6e21\u523064\u4f4d\u4f53\u7cfb\u7684\u8fc7\u7a0b\u4e2d\uff0cINTO\u6307\u4ee4\u548cBOUND\u6307\u4ee4\u90fd\u88ab\u53ea\u7559\u5728\u5386\u53f2\u7684\u5c18\u57c3\u4e4b\u4e2d\u4e86\u3002<\/p>\n<p>copyright ykyi.net<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u539f\u6587:&nbsp;http:\/\/avikivity.blogspot.com\/2011\/08\/c-assembly-and-security.html ykyi.net \u7ffb\u8bd1\u3002 \u6211\u4eec\u770b\u4e0b\u9762\u4e00\u4e2aC\u8bed\u8a00\u7684\u53e5\u5b50\uff1a a = b + c \u4ec0\u4e48\u65f6\u5019\u8fd9\u4e2a\u53e5\u5b50\u4f1a\u9020\u6210\u9519\u8bef\u5462\uff1f 1. a, b, c \u4e0d\u662f\u6211\u4eec\u60f3\u8981\u7684\u503c\u3002\u4e5f\u5c31\u662f\u6211\u4eec\u628a\u53d8\u91cf\u540d\u5199\u9519\u4e86\u3002 2. \u5199\u4e86\u52a0\u6cd5\uff0c\u4f46\u662f\u6211\u4eec\u8981\u7684\u4e0d\u662f\u52a0\u6cd5\u3002 3. \u505a\u4e86\u52a0\u6cd5\u540e\u503c\u6ea2\u51fa\u4e86\u3002 4. a\u548cb\u662f\u65e0\u7b26\u53f7\u7c7b\u578b\uff0c\u800cc\u5374\u662f\u6709\u7b26\u53f7\u7c7b\u578b\u5e76\u4e14\u662f\u8d1f\u6570\uff0cb+c\u540e\u5f97\u5230\u8d1f\u6570\u53c8\u8d4b\u7ed9a. 5. sizeof(a)\u6bd4sizeof(b)\u548csizeof(c)\u8981\u5c0f\u3002\u53c8\u6ea2\u51fa\u4e86\uff01 6. a\u662f\u6709\u7b26\u53f7\u578b\uff0cb\u548cc\u662f\u65e0\u7b26\u53f7\u578b\u3002b+c\u540e\u8d4b\u7ed9a\uff0c\u6ea2\u51fa\u540e\uff0ca\u53d8\u6210\u8d1f\u503c\u3002 7. a\u662f\u65e0\u7b26\u53f7\u578b\uff0cb\u548cc\u662f\u6709\u7b26\u53f7\u578b\uff1b\u518d\u6b21\u6ea2\u51fa\u3002 \u6211\u4eec\u4e0d\u80fd\u671f\u671bC\u8bed\u8a00\u672c\u8eab\u80fd\u907f\u514d\u6240\u6709\u8fd9\u4e9b\u9519\u8bef\uff0c\u4f46\u6211\u4eec\u53ef\u4e0d\u53ef\u4ee5\u901a\u8fc7\u5728\u8fd0\u884c\u65f6Trap\u4e0a\u8ff0\u7684\u4e00\u4e9b\u9519\u8bef\u6539\u8fdbC\u8bed\u8a00\u4f7f\u4e4b\u66f4\u5b89\u5168\u5462\uff1f\u7ed3\u679c\u65f6\uff0c\u9664\u975e\u727a\u7272\u6027\u80fd\uff0c\u5426\u5219\u505a\u4e0d\u5230\u3002\u4f46\u6211\u4eec\u80fd\u727a\u7272\u6027\u80fd\u5417\uff1f &nbsp; &diams; \u4e3a\u4e86\u5904\u7406\u7b2c(3)\u79cd\u60c5\u51b5\uff0c\u6211\u4eec\u9700\u8981Trap\u6240\u4ee5\u6709\u7b26\u53f7\u6570\u7684\u52a0\u6cd5\u548c\u6240\u4ee5\u65e0\u7b26\u53f7\u6570\u7684\u52a0\u6cd5\u6307\u4ee4\u3002 &diams; \u4e3a\u4e86\u5904\u7406\u7b2c(4)\u79cd\u60c5\u51b5\uff0c\u9700\u8981\u4e00\u4e2a\u6df7\u6742\u6709\u7b26\u53f7\u548c\u65e0\u7b26\u53f7\u7684\u52a0\u6cd5\u6307\u4ee4\u88abTrap\u3002 &diams; \u4e3a\u4e86\u5904\u7406\u7b2c(5)\u79cd\u60c5\u51b5\uff0c\u9700\u8981Trap\u5b58\u50a8\u6709\u7b26\u53f7\u6570\u548c\u65e0\u7b26\u53f7\u6570\u7684\u6307\u4ee4\u3002\u5728Trap\u4e2d\u68c0\u67e5\u5bc4\u5b58\u5668\u4e2d\u7684\u503c\u4e0e\u5b58\u5165\u7684\u5185\u5b58\u5730\u5740\u662f\u5426\u5339\u914d\u3002 &diams; (6)\u548c(7)\u4e0e\u4e0a\u7c7b\u4f3c\u3002 &nbsp; \u8fd9\u4e9b\u770b\u4f3c\u7b80\u5355\u7684\u95ee\u9898\u5728\u5b89\u5168\uff0c\u6f0f\u6d1e\u65b9\u9762\u7ecf\u5e38\u51fa\u73b0\u3002\u6211\u4eec\u5f88\u96be\u53d1\u73b0\u5e76\u4fee\u590d\u8fd9\u4e9b\u95ee\u9898\uff0c\u56e0\u4e3a\u6ca1\u6709\u6240\u9700\u8981\u7684\u5904\u7406\u5668\u6307\u4ee4\u3002\u5f53\u7136\u6211\u4eec\u53ef\u4ee5\u7528\u5df2\u7ecf\u5b58\u5728\u7684\u6307\u4ee4\u6a21\u62df\u5b83\u4eec\u3002\u4f46\u662f\u8fd9\u6837\u505a\u80af\u5b9a\u4f1a\u635f\u5bb3\u6027\u80fd\u5e76\u4e14\u4f7f\u7a0b\u5e8f\u7684\u4f53\u79ef\u589e\u5927\u3002\u56e0\u4e3a\u7a0b\u5e8f\u6027\u80fd\u662f\u53ef\u4ee5\u88ab\u5ea6\u91cf\u7684\uff0c\u800c\u5ea6\u91cf\u5b89\u5168\u95ee\u9898\u5219\u6bd4\u8f83\u56f0\u96be\u3002\u7ed3\u679c\u65f6\u7559\u4e0b\u4e86\u5f88\u591a\u5145\u6ee1\u6f0f\u6d1e\u7684\u4ee3\u7801(exploitable code)\u3002 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