linux-kernel - Re: [PATCH] fgraph: Make sure fregs is non-null when accessing

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Message-ID: <20260107101611.527f0772@gandalf.local.home>
Date: Wed, 7 Jan 2026 10:16:11 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: sunliming@...ux.dev
Cc: mhiramat@...nel.org, mark.rutland@....com,
 mathieu.desnoyers@...icios.com, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, sunliming <sunliming@...inos.cn>,
 kernel test robot <lkp@...el.com>, Dan Carpenter <error27@...il.com>
Subject: Re: [PATCH] fgraph: Make sure fregs is non-null when accessing

On Wed,  7 Jan 2026 09:51:25 +0800
sunliming@...ux.dev wrote:

> From: sunliming <sunliming@...inos.cn>
> 
> Fix below smatch warnings:
> kernel/trace/fgraph.c:834 __ftrace_return_to_handler() error: we previously
> assumed 'fregs' could be null (see line 830)
> 

NACK!

> Reported-by: kernel test robot <lkp@...el.com>
> Reported-by: Dan Carpenter <error27@...il.com>
> Closes: https://lore.kernel.org/r/202512131657.JQUt5fXQ-lkp@intel.com/

Really? Did you not read this thread you are "closing"?

-- Steve

> Signed-off-by: sunliming <sunliming@...inos.cn>
> ---
>  kernel/trace/fgraph.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index cc48d16be43e..0f50a55032c5 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -837,7 +837,8 @@ __ftrace_return_to_handler(struct ftrace_regs *fregs, unsigned long frame_pointe
>  		goto out;
>  
>  #ifdef CONFIG_FUNCTION_GRAPH_RETVAL
> -	trace.retval = ftrace_regs_get_return_value(fregs);
> +	if (fregs)
> +		trace.retval = ftrace_regs_get_return_value(fregs);
>  #endif
>  
>  	bitmap = get_bitmap_bits(current, offset);