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SubjectRe: [PATCH] lkdtm: reduce stack size
Hi Frank,

On Sun, Mar 01, 2009 at 09:00:14PM +0100, Frank Seidel wrote:
> From: Frank Seidel <frank@f-seidel.de>
>
> Reduce stack memory footprint of lkdtm
> (recursive_loop). From 1024 bytes on i386 down
> to <10.
>

The intention here is infact to trigger a stack overflow. This module is
used to test kernel dumping mechanism like kdump. So the expectation is
that the kernel will dump as soon as the stack overflows.

> Signed-off-by: Frank Seidel <frank@f-seidel.de>
> ---
> drivers/misc/lkdtm.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> --- a/drivers/misc/lkdtm.c
> +++ b/drivers/misc/lkdtm.c
> @@ -225,14 +225,24 @@ static int lkdtm_parse_commandline(void)
>
> static int recursive_loop(int a)
> {
> - char buf[1024];
> + char *buf;
> + int ret;
> +
> + buf = kmalloc(1024, GFP_KERNEL);
> + if (!buf) {
> + printk(KERN_ERR "lkdtm : couldn't allocate buffer\n");
> + return -ENOMEM;
> + }
>
> memset(buf,0xFF,1024);
> recur_count--;
> if (!recur_count)
> - return 0;
> + ret = 0;
> else
> - return recursive_loop(a);
> + ret = recursive_loop(a);
> +
> + kfree(buf);
> + return ret;
> }
>
> void lkdtm_handler(void)

--
Regards,
Ankita Garg (ankita@in.ibm.com)
Linux Technology Center
IBM India Systems & Technology Labs,
Bangalore, India


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