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

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Message-ID: <18199AAD941A4071B7FD8A0D6C67733A@zhaoleiwin>
Date:	Fri, 13 Mar 2009 17:30:40 +0800
From:	"Zhaolei" <zhaolei@...fujitsu.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	"Steven Rostedt ;" <rostedt@...dmis.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ftrace: Avoid double-free of dyn_ftrace

* From: "Ingo Molnar" <mingo@...e.hu>
> 
> * 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?
Hello, Ingo

It is found via code review.

B.R.
Zhaolei
> 
> Ingo
> 
>