2008-02-20 10:15:21

by Srinivasa Ds

Subject: [RFC] [PATCH] Refuse kprobe insertion on add/sub_preempt_counter()

Kprobes makes use of preempt_disable(),preempt_enable_noresched() and these
functions inturn call add/sub_preempt_count(). So we need to refuse user from
inserting probe in to these functions.

This patch disallows user from probing add/sub_preempt_count().

Signed-off-by: Srinivasa DS <[email protected]>


---
kernel/sched.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6.25-rc2/kernel/sched.c
===================================================================
--- linux-2.6.25-rc2.orig/kernel/sched.c
+++ linux-2.6.25-rc2/kernel/sched.c
@@ -3766,7 +3766,7 @@ void scheduler_tick(void)

#if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)

-void add_preempt_count(int val)
+void __kprobes add_preempt_count(int val)
{
/*
* Underflow?
@@ -3782,7 +3782,7 @@ void add_preempt_count(int val)
}
EXPORT_SYMBOL(add_preempt_count);

-void sub_preempt_count(int val)
+void __kprobes sub_preempt_count(int val)
{
/*
* Underflow?

2008-02-20 10:37:32

by Ananth N Mavinakayanahalli

Subject: Re: [RFC] [PATCH] Refuse kprobe insertion on add/sub_preempt_counter()

On Wed, Feb 20, 2008 at 03:45:17PM +0530, Srinivasa Ds wrote:
> Kprobes makes use of preempt_disable(),preempt_enable_noresched() and these
> functions inturn call add/sub_preempt_count(). So we need to refuse user from
> inserting probe in to these functions.
>
> This patch disallows user from probing add/sub_preempt_count().
>
> Signed-off-by: Srinivasa DS <[email protected]>

Acked-by: Ananth N Mavinakayanahalli <[email protected]>

> ---
> kernel/sched.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> Index: linux-2.6.25-rc2/kernel/sched.c
> ===================================================================
> --- linux-2.6.25-rc2.orig/kernel/sched.c
> +++ linux-2.6.25-rc2/kernel/sched.c
> @@ -3766,7 +3766,7 @@ void scheduler_tick(void)
>
> #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
>
> -void add_preempt_count(int val)
> +void __kprobes add_preempt_count(int val)
> {
> /*
> * Underflow?
> @@ -3782,7 +3782,7 @@ void add_preempt_count(int val)
> }
> EXPORT_SYMBOL(add_preempt_count);
>
> -void sub_preempt_count(int val)
> +void __kprobes sub_preempt_count(int val)
> {
> /*
> * Underflow?
>
>
> --
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