linux-kernel - Re: [PATCH] x86/traps: Mark do_int3() NOKPROBE

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Date:   Thu, 10 Mar 2022 23:04:24 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Li Huafei <lihuafei1@...wei.com>
Cc:     <peterz@...radead.org>, <tglx@...utronix.de>,
        <alexandre.chartre@...cle.com>, <mhiramat@...nel.org>,
        <mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
        <x86@...nel.org>, <hpa@...or.com>, <laijs@...ux.alibaba.com>,
        <chang.seok.bae@...el.com>, <fenghua.yu@...el.com>,
        <thomas.tai@...cle.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/traps: Mark do_int3() NOKPROBE_SYMBOL

On Thu, 10 Mar 2022 20:09:15 +0800
Li Huafei <lihuafei1@...wei.com> wrote:

> Since kprobe_int3_handler() is called in do_int3(), probing do_int3()
> can cause a breakpoint recursion and crash the kernel. Therefore,
> do_int3() should be marked as NOKPROBE_SYMBOL.
> 
> Fixes: 21e28290b317 ("x86/traps: Split int3 handler up")
> Signed-off-by: Li Huafei <lihuafei1@...wei.com>

Good catch!
This should be backported to stable kernel.

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>
Cc: stable@...r.kernel.org


Thank you,

> ---
>  arch/x86/kernel/traps.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index c9d566dcf89a..8143693a7ea6 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -659,6 +659,7 @@ static bool do_int3(struct pt_regs *regs)
>  
>  	return res == NOTIFY_STOP;
>  }
> +NOKPROBE_SYMBOL(do_int3);
>  
>  static void do_int3_user(struct pt_regs *regs)
>  {
> -- 
> 2.17.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>