Hello, Following code (written just for fun) leads to:
Program received signal SIGSEGV, Segmentation fault.
main () at main-general.cpp:95
95 printf("%d\n", x_reg);
BTW, there is warning when using ecx, eax, edx.
should there be any warning for esp?
GCC 4.4
X86
Compile flags: -g3 -O2
---
volatile register int x_reg asm ("esp");
int ff_()
{
x_reg = rand();
return x_reg;
}
int main()
{
x_reg = ff_();
x_reg++;
printf("%d\n", x_reg);
return 1;
}
Dump of assembler code for function _Z3ff_v:
0x080489c0 <_Z3ff_v+0>: push %ebp
0x080489c1 <_Z3ff_v+1>: mov %esp,%ebp
0x080489c3 <_Z3ff_v+3>: sub $0x8,%esp
0x080489c6 <_Z3ff_v+6>: call 0x80487a4 <r...@plt>
0x080489cb <_Z3ff_v+11>: mov %eax,%esp
0x080489cd <_Z3ff_v+13>: mov %esp,%eax
0x080489cf <_Z3ff_v+15>: leave
0x080489d0 <_Z3ff_v+16>: ret
(gdb) disassemble main
Dump of assembler code for function main:
0x080489e0 <main+0>: push %ebp
0x080489e1 <main+1>: mov %esp,%ebp
0x080489e3 <main+3>: and $0xfffffff0,%esp
0x080489e6 <main+6>: sub $0x10,%esp
0x080489e9 <main+9>: call 0x80489c0 <_Z3ff_v>
0x080489ee <main+14>: lea 0x1(%eax),%esp
0x080489f1 <main+17>: mov %esp,0x4(%esp)
0x080489f5 <main+21>: movl $0x8048bd0,(%esp)
0x080489fc <main+28>: call 0x8048774 <pri...@plt> <<
0x08048a01 <main+33>: mov $0x1,%eax
0x08048a06 <main+38>: leave
0x08048a07 <main+39>: ret
Sergey
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