linux-kernel - Re: [patch V4 part 1 15/36] kprobes: Lock kprobe_mutex while showing kprobe

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Date:   Wed, 6 May 2020 17:38:32 +0200
From:   Alexandre Chartre <alexandre.chartre@...cle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>
Subject: Re: [patch V4 part 1 15/36] kprobes: Lock kprobe_mutex while showing
 kprobe_blacklist


On 5/5/20 3:16 PM, Thomas Gleixner wrote:
> From: Masami Hiramatsu <mhiramat@...nel.org>
> 
> Lock kprobe_mutex while showing kprobe_blacklist to prevent updating the
> kprobe_blacklist.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Link: https://lkml.kernel.org/r/158523417665.24735.10253198878535635600.stgit@devnote2
> 
> ---
>   kernel/kprobes.c |    8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)

Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>

alex.

> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2426,6 +2426,7 @@ static const struct file_operations debu
>   /* kprobes/blacklist -- shows which functions can not be probed */
>   static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
>   {
> +	mutex_lock(&kprobe_mutex);
>   	return seq_list_start(&kprobe_blacklist, *pos);
>   }
>   
> @@ -2452,10 +2453,15 @@ static int kprobe_blacklist_seq_show(str
>   	return 0;
>   }
>   
> +static void kprobe_blacklist_seq_stop(struct seq_file *f, void *v)
> +{
> +	mutex_unlock(&kprobe_mutex);
> +}
> +
>   static const struct seq_operations kprobe_blacklist_seq_ops = {
>   	.start = kprobe_blacklist_seq_start,
>   	.next  = kprobe_blacklist_seq_next,
> -	.stop  = kprobe_seq_stop,	/* Reuse void function */
> +	.stop  = kprobe_blacklist_seq_stop,
>   	.show  = kprobe_blacklist_seq_show,
>   };
>   
>