linux-kernel - Re: [PATCH 1/2] tracing/probes: Fix to avoid double count of the string length on the array

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Message-ID: <20230701210840.5cb46a79@rorschach.local.home>
Date:   Sat, 1 Jul 2023 21:08:40 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc:     Dan Carpenter <dan.carpenter@...aro.org>,
        linux-trace-kernel@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] tracing/probes: Fix to avoid double count of the
 string length on the array

On Thu, 29 Jun 2023 23:13:37 +0900
"Masami Hiramatsu (Google)" <mhiramat@...nel.org> wrote:

> From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> 
> If there is an array is specified with the ustring or symstr, the length of

 "If there is an array specified with ustring or .." or "If an array is specified with ustring"

I prefer the latter.

> the strings are accumlated on both of 'ret' and 'total', which means the
> length is double counted.
> Just set the length to the 'ret' value to aviud double count.

					"avoid"

> 
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Closes: https://lore.kernel.org/all/8819b154-2ba1-43c3-98a2-cbde20892023@moroto.mountain/
> Fixes: 88903c464321 ("tracing/probe: Add ustring type for user-space string")
> Cc: stable@...r.kernel.org
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> ---
>  kernel/trace/trace_probe_tmpl.h |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
> index 00707630788d..4735c5cb76fa 100644
> --- a/kernel/trace/trace_probe_tmpl.h
> +++ b/kernel/trace/trace_probe_tmpl.h
> @@ -156,11 +156,11 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
>  			code++;
>  			goto array;
>  		case FETCH_OP_ST_USTRING:
> -			ret += fetch_store_strlen_user(val + code->offset);
> +			ret = fetch_store_strlen_user(val + code->offset);
>  			code++;
>  			goto array;
>  		case FETCH_OP_ST_SYMSTR:
> -			ret += fetch_store_symstrlen(val + code->offset);
> +			ret = fetch_store_symstrlen(val + code->offset);

Other than the above,

Reviewed-by: Steven Rostedt (Google) <rostedt@...dmis.org>

-- Steve


>  			code++;
>  			goto array;
>  		default: