csh> gdb example2
GNU gdb 19991004
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This GDB was configured as "i386-redhat-linux"...
(gdb) break main
Breakpoint 1 at 0x80481c1: file example2.c, line 11.
(gdb) break function
Breakpoint 2 at 0x80481a6: file example2.c, line 4.
(gdb) run
Starting program: /mnt2/data/shlam/bo/example2
Breakpoint 1, main () at example2.c:11
11 for( i = 0; i < 255; i++)
(gdb) disass
Dump of assembler code for function main:
0x80481b8 : push %ebp
0x80481b9 : mov %esp,%ebp
0x80481bb : sub $0x104,%esp
0x80481c1 : nop
0x80481c2 : movl $0x0,0xfffffefc(%ebp)
0x80481cc : lea 0x0(%esi,1),%esi
0x80481d0 : cmpl $0xfe,0xfffffefc(%ebp)
0x80481da : jle 0x80481e0
0x80481dc : jmp 0x80481f8
0x80481de : mov %esi,%esi
0x80481e0 : lea 0xffffff00(%ebp),%eax
0x80481e6 : mov 0xfffffefc(%ebp),%edx
0x80481ec : movb $0x41,(%edx,%eax,1)
0x80481f0 : incl 0xfffffefc(%ebp)
0x80481f6 : jmp 0x80481d0
0x80481f8 : lea 0xffffff00(%ebp),%eax
0x80481fe : push %eax
0x80481ff : call 0x80481a0
0x8048204 : add $0x4,%esp
0x8048207 : leave
0x8048208 : ret
End of assembler dump.
(gdb) info reg
eax 0x0 0
ecx 0x80481b8 134513080
edx 0x807b228 134722088
ebx 0xbffffaa4 -1073743196
esp 0xbffff954 -1073743532
ebp 0xbffffa58 -1073743272
esi 0x1 1
edi 0x0 0
eip 0x80481c1 134513089
eflags 0x282 642
cs 0x23 35
ss 0x2b 43
ds 0x2b 43
es 0x2b 43
fs 0x0 0
gs 0x0 0
cwd 0xffff037f -64641
swd 0xffff0000 -65536
twd 0xffffffff -1
fip 0x0 0
fcs 0x0 0
fopo 0xbffffa3c -1073743300
fos 0x0 0
(gdb) cont
Continuing.
Breakpoint 2, function (str=0xbffff958 'A' ...) at example2.c:4
4 strcpy(buffer,str);
(gdb) disass
Dump of assembler code for function function:
0x80481a0 : push %ebp
0x80481a1 : mov %esp,%ebp
0x80481a3 : sub $0x10,%esp
0x80481a6 : mov 0x8(%ebp),%eax
0x80481a9 : push %eax
0x80481aa : lea 0xfffffff0(%ebp),%eax
0x80481ad : push %eax
0x80481ae : call 0x804cf10
0x80481b3 : add $0x8,%esp
0x80481b6 : leave
0x80481b7 : ret
End of assembler dump.
(gdb) info reg
eax 0xbffff958 -1073743528
ecx 0x80481b8 134513080
edx 0xfe 254
ebx 0xbffffaa4 -1073743196
esp 0xbffff938 -1073743560
ebp 0xbffff948 -1073743544
esi 0x1 1
edi 0x0 0
eip 0x80481a6 134513062
eflags 0x282 642
cs 0x23 35
ss 0x2b 43
ds 0x2b 43
es 0x2b 43
fs 0x0 0
gs 0x0 0
cwd 0xffff037f -64641
swd 0xffff0000 -65536
twd 0xffffffff -1
fip 0x0 0
fcs 0x0 0
fopo 0xbffffa3c -1073743300
fos 0x0 0
(gdb) cont
Continuing.
Program received signal SIGSEGV, Segmentation fault.
0x41414141 in ?? ()
(gdb) info reg
eax 0xbffff938 -1073743560
ecx 0xffffffdf -33
edx 0xbffffa62 -1073743262
ebx 0xbffffaa4 -1073743196
esp 0xbffff950 -1073743536
ebp 0x41414141 1094795585
esi 0x1 1
edi 0x0 0
eip 0x41414141 1094795585
eflags 0x282 642
cs 0x23 35
ss 0x2b 43
ds 0x2b 43
es 0x2b 43
fs 0x0 0
gs 0x0 0
cwd 0xffff037f -64641
swd 0xffff0000 -65536
twd 0xffffffff -1
fip 0x0 0
fcs 0x0 0
fopo 0xbffffa3c -1073743300
fos 0x0 0
(gdb) The program is running. Exit anyway? (y or n) y
Why ebp show all "41" (equivalent to "A" is ASCII)?