Re: can gcc provide information for stack array overran checking ?

[Pawel Sikora <pluto at pld-linux dot org>]

On Tuesday 19 of April 2005 07:36, Xiaoshan Sun wrote:
> hi,
>  the following program has a stack array overran and static arrary overran
> . overran of this kind may be a very hard to find bug in a software .so can
> gcc provide extra information for other debugging tools to check if an
> array is overran ?
> program.c:
>
> int static[5];
>
> int main(void)
> {
>   int stack[5];
>
>   static[5] = 0;
>   stack [5] = 0;
>
>   return 0;
> }
>
> i have no idea about whom to ask ,gdb or gcc or both ??

e.g. gcc-4.x + mudflap switch.

# cat array-overran-checking.c
int _static[5];

int main(void)
{
    int _stack[5];
    _static[5] = 0;
    _stack[5] = 0;
    return 0;
}

# gcc array-overran-checking.c -O2 -fmudflap -lmudflap
# ./a.out
*******
mudflap violation 1 (check/write): time=1113950577.801266 ptr=0x80c9b48 
size=24
pc=0x4002430a location=`array-overran-checking.c:6 (main)'
      /usr/lib/libmudflap.so.0(__mf_check+0x44) [0x4002430a]
      ./a.out(main+0xfe) [0x804884e]
      /usr/lib/libmudflap.so.0(__wrap_main+0x1d8) [0x40025037]
Nearby object 1: checked region begins 0B into and ends 4B after
mudflap object 0x80c9d48: name=`array-overran-checking.c:1 _static'
bounds=[0x80c9b48,0x80c9b5b] size=20 area=static check=0r/3w liveness=3
alloc time=1113950577.801029 pc=0x40024df3
number of nearby objects: 1
*******
mudflap violation 2 (check/write): time=1113950577.802376 ptr=0xbffff458 
size=24
pc=0x4002430a location=`array-overran-checking.c:7 (main)'
      /usr/lib/libmudflap.so.0(__mf_check+0x44) [0x4002430a]
      ./a.out(main+0x136) [0x8048886]
      /usr/lib/libmudflap.so.0(__wrap_main+0x1d8) [0x40025037]
Nearby object 1: checked region begins 0B into and ends 4B after
mudflap object 0x80cb080: name=`array-overran-checking.c:5 (main) _stack'
bounds=[0xbffff458,0xbffff46b] size=20 area=stack check=0r/3w liveness=3
alloc time=1113950577.801240 pc=0x40024df3
number of nearby objects: 1

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