linux-kernel - Re: [PATCH] ftrace: Avoid double-free of dyn

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Message-ID: <20090313092558.GD2571@elte.hu>
Date:	Fri, 13 Mar 2009 10:25:58 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Zhaolei <zhaolei@...fujitsu.com>
Cc:	"Steven Rostedt ;" <rostedt@...dmis.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ftrace: Avoid double-free of dyn_ftrace


* Zhaolei <zhaolei@...fujitsu.com> wrote:

> If dyn_ftrace is free before ftrace_release(), 
> ftrace_release() will free it again and make 
> ftrace_free_records wrong.
> 
> Signed-off-by: Zhao Lei <zhaolei@...fujitsu.com>
> ---
>  kernel/trace/ftrace.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index d33d306..26c45aa 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -356,7 +356,8 @@ void ftrace_release(void *start, unsigned long size)
>  
>  	mutex_lock(&ftrace_lock);
>  	do_for_each_ftrace_rec(pg, rec) {
> -		if ((rec->ip >= s) && (rec->ip < e))
> +		if ((rec->ip >= s) && (rec->ip < e) &&
> +		    !(rec->flags & FTRACE_FL_FREE))
>  			ftrace_free_rec(rec);

Applied to tip:tracing/ftrace, thanks!

I'm wondering, did you trigger this in practice (if yes, how?), 
or have you found it via code review?

	Ingo
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