記錄一次比較容易引起混淆的地方。

#include <stdio.h>

char *str(void) {return "nihao\n"; }int main() {printf("%s\n", str); }

如上圖所示，打印出來的為亂碼。

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直接說結論：

　　此處打印的是str函數的地址，不是"nihao"，這個變量的地址，想要打印出"nihao",應該用 str()。

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下邊又長又屎的分析可以不看，自己犯的迷糊。

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第一反應，字符串 ”nihao“ 是局部變量，從str中返回之后就成亂碼了？

char *str(void) {return "nihao"; }.file "return_str.c".section .rodata .LC0:.string "nihao".text.globl str.type str, @function str: .LFB0:.cfi_startprocpushl %ebp.cfi_def_cfa_offset 8.cfi_offset 5, -8movl %esp, %ebp.cfi_def_cfa_register 5movl $.LC0, %eaxpopl %ebp.cfi_restore 5.cfi_def_cfa 4, 4ret.cfi_endproc .LFE0:.size str, .-str.ident "GCC: (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609".section .note.GNU-stack,"",@progbits

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在.text段，不確定，將地址打印出來看

#include <stdio.h> #include <stdlib.h>int aa;char *test(void) {return "nihao"; }int main() {int bb;static int cc;int *p = (int *)malloc(sizeof(int));char buff[16] = {0};printf("%p\n", &aa);printf("%p\n", &bb);printf("%p\n", &cc);printf("%p\n", p);printf("%p\n", "nihao"); printf("%p\n", test);return 0; }

數據不貼出來了，很明顯，局部變量bb地址跟其他的地址不一致，所以確定字符串”nihao“不是在棧上，不存在函數退出之后訪問不到的情況。

第二反應，返回的是函數地址，通過objdump反匯編，查看返回的的確是函數地址。

a.out： 文件格式 elf32-i386Disassembly of section .interp:08048154 <.interp>:8048154: 2f das 8048155: 6c insb (%dx),%es:(%edi)8048156: 69 62 2f 6c 64 2d 6c imul $0x6c2d646c,0x2f(%edx),%esp804815d: 69 6e 75 78 2e 73 6f imul $0x6f732e78,0x75(%esi),%ebp8048164: 2e 32 00 xor %cs:(%eax),%alDisassembly of section .note.ABI-tag:08048168 <.note.ABI-tag>:8048168: 04 00 add $0x0,%al804816a: 00 00 add %al,(%eax)804816c: 10 00 adc %al,(%eax)804816e: 00 00 add %al,(%eax)8048170: 01 00 add %eax,(%eax)8048172: 00 00 add %al,(%eax)8048174: 47 inc %edi8048175: 4e dec %esi8048176: 55 push %ebp8048177: 00 00 add %al,(%eax)8048179: 00 00 add %al,(%eax)804817b: 00 02 add %al,(%edx)804817d: 00 00 add %al,(%eax)804817f: 00 06 add %al,(%esi)8048181: 00 00 add %al,(%eax)8048183: 00 20 add %ah,(%eax)8048185: 00 00 add %al,(%eax)...Disassembly of section .note.gnu.build-id:08048188 <.note.gnu.build-id>:8048188: 04 00 add $0x0,%al804818a: 00 00 add %al,(%eax)804818c: 14 00 adc $0x0,%al804818e: 00 00 add %al,(%eax)8048190: 03 00 add (%eax),%eax8048192: 00 00 add %al,(%eax)8048194: 47 inc %edi8048195: 4e dec %esi8048196: 55 push %ebp8048197: 00 e4 add %ah,%ah8048199: 0a 2a or (%edx),%ch804819b: 3c f8 cmp $0xf8,%al804819d: ca 5a 61 lret $0x615a80481a0: 85 66 5d test %esp,0x5d(%esi)80481a3: 91 xchg %eax,%ecx80481a4: 72 b5 jb 804815b <_init-0x1b5>80481a6: ca 36 17 lret $0x173680481a9: 77 9f ja 804814a <_init-0x1c6>80481ab: 50 push %eaxDisassembly of section .gnu.hash:080481ac <.gnu.hash>:80481ac: 02 00 add (%eax),%al80481ae: 00 00 add %al,(%eax)80481b0: 06 push %es80481b1: 00 00 add %al,(%eax)80481b3: 00 01 add %al,(%ecx)80481b5: 00 00 add %al,(%eax)80481b7: 00 05 00 00 00 00 add %al,0x080481bd: 20 00 and %al,(%eax)80481bf: 20 00 and %al,(%eax)80481c1: 00 00 add %al,(%eax)80481c3: 00 06 add %al,(%esi)80481c5: 00 00 add %al,(%eax)80481c7: 00 .byte 0x080481c8: ad lods %ds:(%esi),%eax80481c9: 4b dec %ebx80481ca: e3 c0 jecxz 804818c <_init-0x184>Disassembly of section .dynsym:080481cc <.dynsym>:...80481dc: 2b 00 sub (%eax),%eax...80481e6: 00 00 add %al,(%eax)80481e8: 12 00 adc (%eax),%al80481ea: 00 00 add %al,(%eax)80481ec: 1a 00 sbb (%eax),%al...80481f6: 00 00 add %al,(%eax)80481f8: 12 00 adc (%eax),%al80481fa: 00 00 add %al,(%eax)80481fc: 32 00 xor (%eax),%al...8048206: 00 00 add %al,(%eax)8048208: 12 00 adc (%eax),%al804820a: 00 00 add %al,(%eax)804820c: 4b dec %ebx...8048215: 00 00 add %al,(%eax)8048217: 00 20 add %ah,(%eax)8048219: 00 00 add %al,(%eax)804821b: 00 39 add %bh,(%ecx)...8048225: 00 00 add %al,(%eax)8048227: 00 12 add %dl,(%edx)8048229: 00 00 add %al,(%eax)804822b: 00 0b add %cl,(%ebx)804822d: 00 00 add %al,(%eax)804822f: 00 ec add %ch,%ah8048231: 85 04 08 test %eax,(%eax,%ecx,1)8048234: 04 00 add $0x0,%al8048236: 00 00 add %al,(%eax)8048238: 11 00 adc %eax,(%eax)804823a: 10 00 adc %al,(%eax)Disassembly of section .dynstr:0804823c <.dynstr>:804823c: 00 6c 69 62 add %ch,0x62(%ecx,%ebp,2)8048240: 63 2e arpl %bp,(%esi)8048242: 73 6f jae 80482b3 <_init-0x5d>8048244: 2e 36 00 5f 49 cs add %bl,%ss:0x49(%edi)8048249: 4f dec %edi804824a: 5f pop %edi804824b: 73 74 jae 80482c1 <_init-0x4f>804824d: 64 69 6e 5f 75 73 65 imul $0x64657375,%fs:0x5f(%esi),%ebp8048254: 64 8048255: 00 5f 5f add %bl,0x5f(%edi)8048258: 73 74 jae 80482ce <_init-0x42>804825a: 61 popa 804825b: 63 6b 5f arpl %bp,0x5f(%ebx)804825e: 63 68 6b arpl %bp,0x6b(%eax)8048261: 5f pop %edi8048262: 66 61 popaw 8048264: 69 6c 00 70 72 69 6e imul $0x746e6972,0x70(%eax,%eax,1),%ebp804826b: 74 804826c: 66 00 6d 61 data16 add %ch,0x61(%ebp)8048270: 6c insb (%dx),%es:(%edi)8048271: 6c insb (%dx),%es:(%edi)8048272: 6f outsl %ds:(%esi),(%dx)8048273: 63 00 arpl %ax,(%eax)8048275: 5f pop %edi8048276: 5f pop %edi8048277: 6c insb (%dx),%es:(%edi)8048278: 69 62 63 5f 73 74 61 imul $0x6174735f,0x63(%edx),%esp804827f: 72 74 jb 80482f5 <_init-0x1b>8048281: 5f pop %edi8048282: 6d insl (%dx),%es:(%edi)8048283: 61 popa 8048284: 69 6e 00 5f 5f 67 6d imul $0x6d675f5f,0x0(%esi),%ebp804828b: 6f outsl %ds:(%esi),(%dx)804828c: 6e outsb %ds:(%esi),(%dx)804828d: 5f pop %edi804828e: 73 74 jae 8048304 <_init-0xc>8048290: 61 popa 8048291: 72 74 jb 8048307 <_init-0x9>8048293: 5f pop %edi8048294: 5f pop %edi8048295: 00 47 4c add %al,0x4c(%edi)8048298: 49 dec %ecx8048299: 42 inc %edx804829a: 43 inc %ebx804829b: 5f pop %edi804829c: 32 2e xor (%esi),%ch804829e: 34 00 xor $0x0,%al80482a0: 47 inc %edi80482a1: 4c dec %esp80482a2: 49 dec %ecx80482a3: 42 inc %edx80482a4: 43 inc %ebx80482a5: 5f pop %edi80482a6: 32 2e xor (%esi),%ch80482a8: 30 00 xor %al,(%eax)Disassembly of section .gnu.version:080482aa <.gnu.version>:80482aa: 00 00 add %al,(%eax)80482ac: 02 00 add (%eax),%al80482ae: 03 00 add (%eax),%eax80482b0: 02 00 add (%eax),%al80482b2: 00 00 add %al,(%eax)80482b4: 02 00 add (%eax),%al80482b6: 01 00 add %eax,(%eax)Disassembly of section .gnu.version_r:080482b8 <.gnu.version_r>:80482b8: 01 00 add %eax,(%eax)80482ba: 02 00 add (%eax),%al80482bc: 01 00 add %eax,(%eax)80482be: 00 00 add %al,(%eax)80482c0: 10 00 adc %al,(%eax)80482c2: 00 00 add %al,(%eax)80482c4: 00 00 add %al,(%eax)80482c6: 00 00 add %al,(%eax)80482c8: 14 69 adc $0x69,%al80482ca: 69 0d 00 00 03 00 5a imul $0x5a,0x30000,%ecx80482d1: 00 00 00 80482d4: 10 00 adc %al,(%eax)80482d6: 00 00 add %al,(%eax)80482d8: 10 69 69 adc %ch,0x69(%ecx)80482db: 0d 00 00 02 00 or $0x20000,%eax80482e0: 64 00 00 add %al,%fs:(%eax)80482e3: 00 00 add %al,(%eax)80482e5: 00 00 add %al,(%eax)...Disassembly of section .rel.dyn:080482e8 <.rel.dyn>:80482e8: fc cld 80482e9: 9f lahf 80482ea: 04 08 add $0x8,%al80482ec: 06 push %es80482ed: 04 00 add $0x0,%al...Disassembly of section .rel.plt:080482f0 <.rel.plt>:80482f0: 0c a0 or $0xa0,%al80482f2: 04 08 add $0x8,%al80482f4: 07 pop %es80482f5: 01 00 add %eax,(%eax)80482f7: 00 10 add %dl,(%eax)80482f9: a0 04 08 07 02 mov 0x2070804,%al80482fe: 00 00 add %al,(%eax)8048300: 14 a0 adc $0xa0,%al8048302: 04 08 add $0x8,%al8048304: 07 pop %es8048305: 03 00 add (%eax),%eax8048307: 00 18 add %bl,(%eax)8048309: a0 04 08 07 05 mov 0x5070804,%al...Disassembly of section .init:08048310 <_init>:8048310: 53 push %ebx8048311: 83 ec 08 sub $0x8,%esp8048314: e8 b7 00 00 00 call 80483d0 <__x86.get_pc_thunk.bx>8048319: 81 c3 e7 1c 00 00 add $0x1ce7,%ebx804831f: 8b 83 fc ff ff ff mov -0x4(%ebx),%eax8048325: 85 c0 test %eax,%eax8048327: 74 05 je 804832e <_init+0x1e>8048329: e8 62 00 00 00 call 8048390 <__libc_start_main@plt+0x10>804832e: 83 c4 08 add $0x8,%esp8048331: 5b pop %ebx8048332: c3 ret Disassembly of section .plt:08048340 <printf@plt-0x10>:8048340: ff 35 04 a0 04 08 pushl 0x804a0048048346: ff 25 08 a0 04 08 jmp *0x804a008804834c: 00 00 add %al,(%eax)...08048350 <printf@plt>:8048350: ff 25 0c a0 04 08 jmp *0x804a00c8048356: 68 00 00 00 00 push $0x0804835b: e9 e0 ff ff ff jmp 8048340 <_init+0x30>08048360 <__stack_chk_fail@plt>:8048360: ff 25 10 a0 04 08 jmp *0x804a0108048366: 68 08 00 00 00 push $0x8804836b: e9 d0 ff ff ff jmp 8048340 <_init+0x30>08048370 <malloc@plt>:8048370: ff 25 14 a0 04 08 jmp *0x804a0148048376: 68 10 00 00 00 push $0x10804837b: e9 c0 ff ff ff jmp 8048340 <_init+0x30>08048380 <__libc_start_main@plt>:8048380: ff 25 18 a0 04 08 jmp *0x804a0188048386: 68 18 00 00 00 push $0x18804838b: e9 b0 ff ff ff jmp 8048340 <_init+0x30>Disassembly of section .plt.got:08048390 <.plt.got>:8048390: ff 25 fc 9f 04 08 jmp *0x8049ffc8048396: 66 90 xchg %ax,%axDisassembly of section .text:080483a0 <_start>:80483a0: 31 ed xor %ebp,%ebp80483a2: 5e pop %esi80483a3: 89 e1 mov %esp,%ecx80483a5: 83 e4 f0 and $0xfffffff0,%esp80483a8: 50 push %eax80483a9: 54 push %esp80483aa: 52 push %edx80483ab: 68 d0 85 04 08 push $0x80485d080483b0: 68 70 85 04 08 push $0x804857080483b5: 51 push %ecx80483b6: 56 push %esi80483b7: 68 a5 84 04 08 push $0x80484a580483bc: e8 bf ff ff ff call 8048380 <__libc_start_main@plt>80483c1: f4 hlt 80483c2: 66 90 xchg %ax,%ax80483c4: 66 90 xchg %ax,%ax80483c6: 66 90 xchg %ax,%ax80483c8: 66 90 xchg %ax,%ax80483ca: 66 90 xchg %ax,%ax80483cc: 66 90 xchg %ax,%ax80483ce: 66 90 xchg %ax,%ax080483d0 <__x86.get_pc_thunk.bx>:80483d0: 8b 1c 24 mov (%esp),%ebx80483d3: c3 ret 80483d4: 66 90 xchg %ax,%ax80483d6: 66 90 xchg %ax,%ax80483d8: 66 90 xchg %ax,%ax80483da: 66 90 xchg %ax,%ax80483dc: 66 90 xchg %ax,%ax80483de: 66 90 xchg %ax,%ax080483e0 <deregister_tm_clones>:80483e0: b8 27 a0 04 08 mov $0x804a027,%eax80483e5: 2d 24 a0 04 08 sub $0x804a024,%eax80483ea: 83 f8 06 cmp $0x6,%eax80483ed: 76 1a jbe 8048409 <deregister_tm_clones+0x29>80483ef: b8 00 00 00 00 mov $0x0,%eax80483f4: 85 c0 test %eax,%eax80483f6: 74 11 je 8048409 <deregister_tm_clones+0x29>80483f8: 55 push %ebp80483f9: 89 e5 mov %esp,%ebp80483fb: 83 ec 14 sub $0x14,%esp80483fe: 68 24 a0 04 08 push $0x804a0248048403: ff d0 call *%eax8048405: 83 c4 10 add $0x10,%esp8048408: c9 leave 8048409: f3 c3 repz ret 804840b: 90 nop804840c: 8d 74 26 00 lea 0x0(%esi,%eiz,1),%esi08048410 <register_tm_clones>:8048410: b8 24 a0 04 08 mov $0x804a024,%eax8048415: 2d 24 a0 04 08 sub $0x804a024,%eax804841a: c1 f8 02 sar $0x2,%eax804841d: 89 c2 mov %eax,%edx804841f: c1 ea 1f shr $0x1f,%edx8048422: 01 d0 add %edx,%eax8048424: d1 f8 sar %eax8048426: 74 1b je 8048443 <register_tm_clones+0x33>8048428: ba 00 00 00 00 mov $0x0,%edx804842d: 85 d2 test %edx,%edx804842f: 74 12 je 8048443 <register_tm_clones+0x33>8048431: 55 push %ebp8048432: 89 e5 mov %esp,%ebp8048434: 83 ec 10 sub $0x10,%esp8048437: 50 push %eax8048438: 68 24 a0 04 08 push $0x804a024804843d: ff d2 call *%edx804843f: 83 c4 10 add $0x10,%esp8048442: c9 leave 8048443: f3 c3 repz ret 8048445: 8d 74 26 00 lea 0x0(%esi,%eiz,1),%esi8048449: 8d bc 27 00 00 00 00 lea 0x0(%edi,%eiz,1),%edi08048450 <__do_global_dtors_aux>:8048450: 80 3d 24 a0 04 08 00 cmpb $0x0,0x804a0248048457: 75 13 jne 804846c <__do_global_dtors_aux+0x1c>8048459: 55 push %ebp804845a: 89 e5 mov %esp,%ebp804845c: 83 ec 08 sub $0x8,%esp804845f: e8 7c ff ff ff call 80483e0 <deregister_tm_clones>8048464: c6 05 24 a0 04 08 01 movb $0x1,0x804a024804846b: c9 leave 804846c: f3 c3 repz ret 804846e: 66 90 xchg %ax,%ax08048470 <frame_dummy>:8048470: b8 10 9f 04 08 mov $0x8049f10,%eax8048475: 8b 10 mov (%eax),%edx8048477: 85 d2 test %edx,%edx8048479: 75 05 jne 8048480 <frame_dummy+0x10>804847b: eb 93 jmp 8048410 <register_tm_clones>804847d: 8d 76 00 lea 0x0(%esi),%esi8048480: ba 00 00 00 00 mov $0x0,%edx8048485: 85 d2 test %edx,%edx8048487: 74 f2 je 804847b <frame_dummy+0xb>8048489: 55 push %ebp804848a: 89 e5 mov %esp,%ebp804848c: 83 ec 14 sub $0x14,%esp804848f: 50 push %eax8048490: ff d2 call *%edx8048492: 83 c4 10 add $0x10,%esp8048495: c9 leave 8048496: e9 75 ff ff ff jmp 8048410 <register_tm_clones>0804849b <test>:804849b: 55 push %ebp804849c: 89 e5 mov %esp,%ebp804849e: b8 f0 85 04 08 mov $0x80485f0,%eax80484a3: 5d pop %ebp80484a4: c3 ret 080484a5 <main>:80484a5: 8d 4c 24 04 lea 0x4(%esp),%ecx80484a9: 83 e4 f0 and $0xfffffff0,%esp80484ac: ff 71 fc pushl -0x4(%ecx)80484af: 55 push %ebp80484b0: 89 e5 mov %esp,%ebp80484b2: 51 push %ecx80484b3: 83 ec 14 sub $0x14,%esp80484b6: 65 a1 14 00 00 00 mov %gs:0x14,%eax80484bc: 89 45 f4 mov %eax,-0xc(%ebp)80484bf: 31 c0 xor %eax,%eax80484c1: 83 ec 0c sub $0xc,%esp80484c4: 6a 04 push $0x480484c6: e8 a5 fe ff ff call 8048370 <malloc@plt>80484cb: 83 c4 10 add $0x10,%esp80484ce: 89 45 f0 mov %eax,-0x10(%ebp)80484d1: 83 ec 08 sub $0x8,%esp80484d4: 68 2c a0 04 08 push $0x804a02c80484d9: 68 f6 85 04 08 push $0x80485f680484de: e8 6d fe ff ff call 8048350 <printf@plt>80484e3: 83 c4 10 add $0x10,%esp80484e6: 83 ec 08 sub $0x8,%esp80484e9: 8d 45 ec lea -0x14(%ebp),%eax80484ec: 50 push %eax80484ed: 68 f6 85 04 08 push $0x80485f680484f2: e8 59 fe ff ff call 8048350 <printf@plt>80484f7: 83 c4 10 add $0x10,%esp80484fa: 83 ec 08 sub $0x8,%esp80484fd: 68 28 a0 04 08 push $0x804a0288048502: 68 f6 85 04 08 push $0x80485f68048507: e8 44 fe ff ff call 8048350 <printf@plt>804850c: 83 c4 10 add $0x10,%esp804850f: 83 ec 08 sub $0x8,%esp8048512: ff 75 f0 pushl -0x10(%ebp)8048515: 68 f6 85 04 08 push $0x80485f6804851a: e8 31 fe ff ff call 8048350 <printf@plt>804851f: 83 c4 10 add $0x10,%esp8048522: 83 ec 08 sub $0x8,%esp8048525: 68 f0 85 04 08 push $0x80485f0804852a: 68 f6 85 04 08 push $0x80485f6804852f: e8 1c fe ff ff call 8048350 <printf@plt>8048534: 83 c4 10 add $0x10,%esp8048537: 83 ec 08 sub $0x8,%esp804853a: 68 9b 84 04 08 push $0x804849b804853f: 68 f6 85 04 08 push $0x80485f68048544: e8 07 fe ff ff call 8048350 <printf@plt>8048549: 83 c4 10 add $0x10,%esp804854c: b8 00 00 00 00 mov $0x0,%eax8048551: 8b 55 f4 mov -0xc(%ebp),%edx8048554: 65 33 15 14 00 00 00 xor %gs:0x14,%edx804855b: 74 05 je 8048562 <main+0xbd>804855d: e8 fe fd ff ff call 8048360 <__stack_chk_fail@plt>8048562: 8b 4d fc mov -0x4(%ebp),%ecx8048565: c9 leave 8048566: 8d 61 fc lea -0x4(%ecx),%esp8048569: c3 ret 804856a: 66 90 xchg %ax,%ax804856c: 66 90 xchg %ax,%ax804856e: 66 90 xchg %ax,%ax08048570 <__libc_csu_init>:8048570: 55 push %ebp8048571: 57 push %edi8048572: 56 push %esi8048573: 53 push %ebx8048574: e8 57 fe ff ff call 80483d0 <__x86.get_pc_thunk.bx>8048579: 81 c3 87 1a 00 00 add $0x1a87,%ebx804857f: 83 ec 0c sub $0xc,%esp8048582: 8b 6c 24 20 mov 0x20(%esp),%ebp8048586: 8d b3 0c ff ff ff lea -0xf4(%ebx),%esi804858c: e8 7f fd ff ff call 8048310 <_init>8048591: 8d 83 08 ff ff ff lea -0xf8(%ebx),%eax8048597: 29 c6 sub %eax,%esi8048599: c1 fe 02 sar $0x2,%esi804859c: 85 f6 test %esi,%esi804859e: 74 25 je 80485c5 <__libc_csu_init+0x55>80485a0: 31 ff xor %edi,%edi80485a2: 8d b6 00 00 00 00 lea 0x0(%esi),%esi80485a8: 83 ec 04 sub $0x4,%esp80485ab: ff 74 24 2c pushl 0x2c(%esp)80485af: ff 74 24 2c pushl 0x2c(%esp)80485b3: 55 push %ebp80485b4: ff 94 bb 08 ff ff ff call *-0xf8(%ebx,%edi,4)80485bb: 83 c7 01 add $0x1,%edi80485be: 83 c4 10 add $0x10,%esp80485c1: 39 f7 cmp %esi,%edi80485c3: 75 e3 jne 80485a8 <__libc_csu_init+0x38>80485c5: 83 c4 0c add $0xc,%esp80485c8: 5b pop %ebx80485c9: 5e pop %esi80485ca: 5f pop %edi80485cb: 5d pop %ebp80485cc: c3 ret 80485cd: 8d 76 00 lea 0x0(%esi),%esi080485d0 <__libc_csu_fini>:80485d0: f3 c3 repz ret Disassembly of section .fini:080485d4 <_fini>:80485d4: 53 push %ebx80485d5: 83 ec 08 sub $0x8,%esp80485d8: e8 f3 fd ff ff call 80483d0 <__x86.get_pc_thunk.bx>80485dd: 81 c3 23 1a 00 00 add $0x1a23,%ebx80485e3: 83 c4 08 add $0x8,%esp80485e6: 5b pop %ebx80485e7: c3 ret Disassembly of section .rodata:080485e8 <_fp_hw>:80485e8: 03 00 add (%eax),%eax...080485ec <_IO_stdin_used>:80485ec: 01 00 add %eax,(%eax)80485ee: 02 00 add (%eax),%al80485f0: 6e outsb %ds:(%esi),(%dx)80485f1: 69 68 61 6f 00 25 70 imul $0x7025006f,0x61(%eax),%ebp80485f8: 0a 00 or (%eax),%alDisassembly of section .eh_frame_hdr:080485fc <__GNU_EH_FRAME_HDR>:80485fc: 01 1b add %ebx,(%ebx)80485fe: 03 3b add (%ebx),%edi8048600: 30 00 xor %al,(%eax)8048602: 00 00 add %al,(%eax)8048604: 05 00 00 00 44 add $0x44000000,%eax8048609: fd std 804860a: ff (bad) 804860b: ff 4c 00 00 decl 0x0(%eax,%eax,1)804860f: 00 9f fe ff ff 70 add %bl,0x70fffffe(%edi)8048615: 00 00 add %al,(%eax)8048617: 00 a9 fe ff ff 90 add %ch,-0x6f000002(%ecx)804861d: 00 00 add %al,(%eax)804861f: 00 74 ff ff add %dh,-0x1(%edi,%edi,8)8048623: ff (bad) 8048624: bc 00 00 00 d4 mov $0xd4000000,%esp8048629: ff (bad) 804862a: ff (bad) 804862b: ff 08 decl (%eax)804862d: 01 00 add %eax,(%eax)...Disassembly of section .eh_frame:08048630 <__FRAME_END__-0xe8>:8048630: 14 00 adc $0x0,%al8048632: 00 00 add %al,(%eax)8048634: 00 00 add %al,(%eax)8048636: 00 00 add %al,(%eax)8048638: 01 7a 52 add %edi,0x52(%edx)804863b: 00 01 add %al,(%ecx)804863d: 7c 08 jl 8048647 <__GNU_EH_FRAME_HDR+0x4b>804863f: 01 1b add %ebx,(%ebx)8048641: 0c 04 or $0x4,%al8048643: 04 88 add $0x88,%al8048645: 01 00 add %eax,(%eax)8048647: 00 20 add %ah,(%eax)8048649: 00 00 add %al,(%eax)804864b: 00 1c 00 add %bl,(%eax,%eax,1)804864e: 00 00 add %al,(%eax)8048650: f0 fc lock cld 8048652: ff (bad) 8048653: ff 50 00 call *0x0(%eax)8048656: 00 00 add %al,(%eax)8048658: 00 0e add %cl,(%esi)804865a: 08 46 0e or %al,0xe(%esi)804865d: 0c 4a or $0x4a,%al804865f: 0f 0b ud2 8048661: 74 04 je 8048667 <__GNU_EH_FRAME_HDR+0x6b>8048663: 78 00 js 8048665 <__GNU_EH_FRAME_HDR+0x69>8048665: 3f aas 8048666: 1a 3b sbb (%ebx),%bh8048668: 2a 32 sub (%edx),%dh804866a: 24 22 and $0x22,%al804866c: 1c 00 sbb $0x0,%al804866e: 00 00 add %al,(%eax)8048670: 40 inc %eax8048671: 00 00 add %al,(%eax)8048673: 00 27 add %ah,(%edi)8048675: fe (bad) 8048676: ff (bad) 8048677: ff 0a decl (%edx)8048679: 00 00 add %al,(%eax)804867b: 00 00 add %al,(%eax)804867d: 41 inc %ecx804867e: 0e push %cs804867f: 08 85 02 42 0d 05 or %al,0x50d4202(%ebp)8048685: 46 inc %esi8048686: c5 0c 04 lds (%esp,%eax,1),%ecx8048689: 04 00 add $0x0,%al804868b: 00 28 add %ch,(%eax)804868d: 00 00 add %al,(%eax)804868f: 00 60 00 add %ah,0x0(%eax)8048692: 00 00 add %al,(%eax)8048694: 11 fe adc %edi,%esi8048696: ff (bad) 8048697: ff c5 inc %ebp8048699: 00 00 add %al,(%eax)804869b: 00 00 add %al,(%eax)804869d: 44 inc %esp804869e: 0c 01 or $0x1,%al80486a0: 00 47 10 add %al,0x10(%edi)80486a3: 05 02 75 00 43 add $0x43007502,%eax80486a8: 0f 03 75 7c lsl 0x7c(%ebp),%esi80486ac: 06 push %es80486ad: 02 b2 0c 01 00 41 add 0x4100010c(%edx),%dh80486b3: c5 43 0c lds 0xc(%ebx),%eax80486b6: 04 04 add $0x4,%al80486b8: 48 dec %eax80486b9: 00 00 add %al,(%eax)80486bb: 00 8c 00 00 00 b0 fe add %cl,-0x1500000(%eax,%eax,1)80486c2: ff (bad) 80486c3: ff 5d 00 lcall *0x0(%ebp)80486c6: 00 00 add %al,(%eax)80486c8: 00 41 0e add %al,0xe(%ecx)80486cb: 08 85 02 41 0e 0c or %al,0xc0e4102(%ebp)80486d1: 87 03 xchg %eax,(%ebx)80486d3: 41 inc %ecx80486d4: 0e push %cs80486d5: 10 86 04 41 0e 14 adc %al,0x140e4104(%esi)80486db: 83 05 4e 0e 20 69 0e addl $0xe,0x69200e4e80486e2: 24 44 and $0x44,%al80486e4: 0e push %cs80486e5: 28 44 0e 2c sub %al,0x2c(%esi,%ecx,1)80486e9: 41 inc %ecx80486ea: 0e push %cs80486eb: 30 4d 0e xor %cl,0xe(%ebp)80486ee: 20 47 0e and %al,0xe(%edi)80486f1: 14 41 adc $0x41,%al80486f3: c3 ret 80486f4: 0e push %cs80486f5: 10 41 c6 adc %al,-0x3a(%ecx)80486f8: 0e push %cs80486f9: 0c 41 or $0x41,%al80486fb: c7 (bad) 80486fc: 0e push %cs80486fd: 08 41 c5 or %al,-0x3b(%ecx)8048700: 0e push %cs8048701: 04 00 add $0x0,%al8048703: 00 10 add %dl,(%eax)8048705: 00 00 add %al,(%eax)8048707: 00 d8 add %bl,%al8048709: 00 00 add %al,(%eax)804870b: 00 c4 add %al,%ah804870d: fe (bad) 804870e: ff (bad) 804870f: ff 02 incl (%edx)8048711: 00 00 add %al,(%eax)8048713: 00 00 add %al,(%eax)8048715: 00 00 add %al,(%eax)...08048718 <__FRAME_END__>:8048718: 00 00 add %al,(%eax)...Disassembly of section .init_array:08049f08 <__frame_dummy_init_array_entry>:8049f08: 70 84 jo 8049e8e <__FRAME_END__+0x1776>8049f0a: 04 08 add $0x8,%alDisassembly of section .fini_array:08049f0c <__do_global_dtors_aux_fini_array_entry>:8049f0c: 50 push %eax8049f0d: 84 04 08 test %al,(%eax,%ecx,1)Disassembly of section .jcr:08049f10 <__JCR_END__>:8049f10: 00 00 add %al,(%eax)...Disassembly of section .dynamic:08049f14 <_DYNAMIC>:8049f14: 01 00 add %eax,(%eax)8049f16: 00 00 add %al,(%eax)8049f18: 01 00 add %eax,(%eax)8049f1a: 00 00 add %al,(%eax)8049f1c: 0c 00 or $0x0,%al8049f1e: 00 00 add %al,(%eax)8049f20: 10 83 04 08 0d 00 adc %al,0xd0804(%ebx)8049f26: 00 00 add %al,(%eax)8049f28: d4 85 aam $0x858049f2a: 04 08 add $0x8,%al8049f2c: 19 00 sbb %eax,(%eax)8049f2e: 00 00 add %al,(%eax)8049f30: 08 9f 04 08 1b 00 or %bl,0x1b0804(%edi)8049f36: 00 00 add %al,(%eax)8049f38: 04 00 add $0x0,%al8049f3a: 00 00 add %al,(%eax)8049f3c: 1a 00 sbb (%eax),%al8049f3e: 00 00 add %al,(%eax)8049f40: 0c 9f or $0x9f,%al8049f42: 04 08 add $0x8,%al8049f44: 1c 00 sbb $0x0,%al8049f46: 00 00 add %al,(%eax)8049f48: 04 00 add $0x0,%al8049f4a: 00 00 add %al,(%eax)8049f4c: f5 cmc 8049f4d: fe (bad) 8049f4e: ff 6f ac ljmp *-0x54(%edi)8049f51: 81 04 08 05 00 00 00 addl $0x5,(%eax,%ecx,1)8049f58: 3c 82 cmp $0x82,%al8049f5a: 04 08 add $0x8,%al8049f5c: 06 push %es8049f5d: 00 00 add %al,(%eax)8049f5f: 00 cc add %cl,%ah8049f61: 81 04 08 0a 00 00 00 addl $0xa,(%eax,%ecx,1)8049f68: 6e outsb %ds:(%esi),(%dx)8049f69: 00 00 add %al,(%eax)8049f6b: 00 0b add %cl,(%ebx)8049f6d: 00 00 add %al,(%eax)8049f6f: 00 10 add %dl,(%eax)8049f71: 00 00 add %al,(%eax)8049f73: 00 15 00 00 00 00 add %dl,0x08049f79: 00 00 add %al,(%eax)8049f7b: 00 03 add %al,(%ebx)8049f7d: 00 00 add %al,(%eax)8049f7f: 00 00 add %al,(%eax)8049f81: a0 04 08 02 00 mov 0x20804,%al8049f86: 00 00 add %al,(%eax)8049f88: 20 00 and %al,(%eax)8049f8a: 00 00 add %al,(%eax)8049f8c: 14 00 adc $0x0,%al8049f8e: 00 00 add %al,(%eax)8049f90: 11 00 adc %eax,(%eax)8049f92: 00 00 add %al,(%eax)8049f94: 17 pop %ss8049f95: 00 00 add %al,(%eax)8049f97: 00 f0 add %dh,%al8049f99: 82 (bad) 8049f9a: 04 08 add $0x8,%al8049f9c: 11 00 adc %eax,(%eax)8049f9e: 00 00 add %al,(%eax)8049fa0: e8 82 04 08 12 call 1a0ca427 <_end+0x120803f7>8049fa5: 00 00 add %al,(%eax)8049fa7: 00 08 add %cl,(%eax)8049fa9: 00 00 add %al,(%eax)8049fab: 00 13 add %dl,(%ebx)8049fad: 00 00 add %al,(%eax)8049faf: 00 08 add %cl,(%eax)8049fb1: 00 00 add %al,(%eax)8049fb3: 00 fe add %bh,%dh8049fb5: ff (bad) 8049fb6: ff 6f b8 ljmp *-0x48(%edi)8049fb9: 82 (bad) 8049fba: 04 08 add $0x8,%al8049fbc: ff (bad) 8049fbd: ff (bad) 8049fbe: ff 6f 01 ljmp *0x1(%edi)8049fc1: 00 00 add %al,(%eax)8049fc3: 00 f0 add %dh,%al8049fc5: ff (bad) 8049fc6: ff 6f aa ljmp *-0x56(%edi)8049fc9: 82 (bad) 8049fca: 04 08 add $0x8,%al...Disassembly of section .got:08049ffc <.got>:8049ffc: 00 00 add %al,(%eax)...Disassembly of section .got.plt:0804a000 <_GLOBAL_OFFSET_TABLE_>:804a000: 14 9f adc $0x9f,%al804a002: 04 08 add $0x8,%al...804a00c: 56 push %esi804a00d: 83 04 08 66 addl $0x66,(%eax,%ecx,1)804a011: 83 04 08 76 addl $0x76,(%eax,%ecx,1)804a015: 83 04 08 86 addl $0xffffff86,(%eax,%ecx,1)804a019: 83 .byte 0x83804a01a: 04 08 add $0x8,%alDisassembly of section .data:0804a01c <__data_start>:804a01c: 00 00 add %al,(%eax)...0804a020 <__dso_handle>:804a020: 00 00 add %al,(%eax)...Disassembly of section .bss:0804a024 <__bss_start>:804a024: 00 00 add %al,(%eax)...0804a028 <cc.2459>:804a028: 00 00 add %al,(%eax)...0804a02c <aa>:804a02c: 00 00 add %al,(%eax)...Disassembly of section .comment:00000000 <.comment>:0: 47 inc %edi1: 43 inc %ebx2: 43 inc %ebx3: 3a 20 cmp (%eax),%ah5: 28 55 62 sub %dl,0x62(%ebp)8: 75 6e jne 78 <_init-0x8048298>a: 74 75 je 81 <_init-0x804828f>c: 20 35 2e 34 2e 30 and %dh,0x302e342e12: 2d 36 75 62 75 sub $0x75627536,%eax17: 6e outsb %ds:(%esi),(%dx)18: 74 75 je 8f <_init-0x8048281>1a: 31 7e 31 xor %edi,0x31(%esi)1d: 36 2e 30 34 2e ss xor %dh,%cs:(%esi,%ebp,1)22: 39 29 cmp %ebp,(%ecx)24: 20 35 2e 34 2e 30 and %dh,0x302e342e2a: 20 32 and %dh,(%edx)2c: 30 31 xor %dh,(%ecx)2e: 36 30 36 xor %dh,%ss:(%esi)31: 30 39 xor %bh,(%ecx)...

繼續懵逼，為什么strcpy可以返回指針，還特地找來glibc的code看了一下，沒看到啥特殊處理。

又寫了一個demo

int *test() {int *p = NULL;p = (int *)malloc(sizeof(int));printf("...%p\n", p);return p; }int main() {int *pp = test();printf("%p\n", test);printf("%p\n", pp); }

?

最后終于瞅出來了

test() 是函數調用，打印時候是return的地址。

test 表示的是函數的指針。

?

學習任何東西，總有一個經常反復，越來越熟悉的過程。

有些覺得會了的東西，掌握的可能不夠不透徹。

轉載于:https://www.cnblogs.com/rivsidn/p/9236423.html

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