Re: protection against buffer overflows

[Alvin Oga <aoga@Maggie.Linux-Consulting.com>]

hi ya ralf

i would have thought that gcc would barf on b[20]='X'
and similarly for theother variable assignments since its not prev
allocated/defined.. and yet explicitly assigned (incorrectly??)...

its lot harder to control when the coder does
strcpy or readln() without first chcking the length of the variables

C-code-checkers
http://www.Linux-Sec.net/Audit/#Code

have fun linuxing
alvin


On Thu, 24 Jan 2002, Ralf Dreibrodt wrote:

> hi,
> 
> >  anyone to offer any
> > explanation will be showered with greatness!
> 
> here is an example:
> 
> #include <stdio.h>
> 
> void example()
> {
>   char a[10];
>   char b[10];
>   strcpy(a, "123456789");
>   printf ("a: %s\n", a);
>   b[20]='X';
>   b[21]='Y';
>   b[22]='Z';
>   printf("a: %s\n", a);
>   return;
> }
> main()
> {
> example();
> }
> 
> debian:/tmp# ./example
> a: 123456789
> a: 12345678XYZ¿|ýÿ¿?0
> 
> now imagine you receive the numbers 20, 21 and 22 and letters X, Y and Z
> from user input.
> 
> bye
> Ralf
> 
> 
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