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SubjectRe: [PATCH 1/2] sched: Add helper for task stack page overrun checking
On 09/04, Aaron Tomlin wrote:
>
> +#define task_stack_end_corrupted(task) \
> + (*(end_of_stack(task)) != STACK_END_MAGIC)

and it is always used along with "tsk != init_task".

But why we exclude swapper/0? Can't we add

end_of_stack(current) = STACK_END_MAGIC;

somewhere at the start of start_kernel() ?

If not, perhaps this new helper should check "task != &init_task"
itself so that we can simplify its users?

Oleg.

>
> static inline int object_is_on_stack(void *obj)
> {
> diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
> index 8a4e5cb..06c7390 100644
> --- a/kernel/trace/trace_stack.c
> +++ b/kernel/trace/trace_stack.c
> @@ -13,7 +13,6 @@
> #include <linux/sysctl.h>
> #include <linux/init.h>
> #include <linux/fs.h>
> -#include <linux/magic.h>
>
> #include <asm/setup.h>
>
> @@ -171,8 +170,8 @@ check_stack(unsigned long ip, unsigned long *stack)
> i++;
> }
>
> - if ((current != &init_task &&
> - *(end_of_stack(current)) != STACK_END_MAGIC)) {
> + if (current != &init_task &&
> + task_stack_end_corrupted(current)) {
> print_max_stack();
> BUG();
> }
> --
> 1.9.3
>



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