linux-kernel - Re: [PATCH v2 2/2] trace: kdb: Replace simple_strtoul with kstrtoul in kdb

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Message-Id: <20241023174944.e85832349ef91ebff9cab31e@kernel.org>
Date: Wed, 23 Oct 2024 17:49:44 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Nir Lichtman <nir@...htman.org>
Cc: kgdb-bugreport@...ts.sourceforge.net,
 linux-trace-kernel@...r.kernel.org, yuran.pereira@...mail.com,
 jason.wessel@...driver.com, daniel.thompson@...aro.org,
 dianders@...omium.org, rostedt@...dmis.org, mhiramat@...nel.org,
 linux-kernel@...r.kernel.org,
 linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH v2 2/2] trace: kdb: Replace simple_strtoul with kstrtoul
 in kdb_ftdump

On Mon, 21 Oct 2024 21:17:24 +0000
Nir Lichtman <nir@...htman.org> wrote:

> The function simple_strtoul performs no error checking in scenarios
> where the input value overflows the intended output variable.
> This results in this function successfully returning, even when the
> output does not match the input string (aka the function returns
> successfully even when the result is wrong).
> 
> Or as it was mentioned [1], "...simple_strtol(), simple_strtoll(),
> simple_strtoul(), and simple_strtoull() functions explicitly ignore
> overflows, which may lead to unexpected results in callers."
> Hence, the use of those functions is discouraged.
> 
> This patch replaces all uses of the simple_strtoul with the safer
> alternatives kstrtoint and kstrtol.
> 
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#simple-strtol-simple-strtoll-simple-strtoul-simple-strtoull
> 

Looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thank you,

> Signed-off-by: Yuran Pereira <yuran.pereira@...mail.com>
> Signed-off-by: Nir Lichtman <nir@...htman.org>
> ---
>  kernel/trace/trace_kdb.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
> index 59857a1ee44c..eadda6e05526 100644
> --- a/kernel/trace/trace_kdb.c
> +++ b/kernel/trace/trace_kdb.c
> @@ -96,23 +96,20 @@ static int kdb_ftdump(int argc, const char **argv)
>  {
>  	int skip_entries = 0;
>  	long cpu_file;
> -	char *cp;
> +	int err;
>  	int cnt;
>  	int cpu;
>  
>  	if (argc > 2)
>  		return KDB_ARGCOUNT;
>  
> -	if (argc) {
> -		skip_entries = simple_strtol(argv[1], &cp, 0);
> -		if (*cp)
> -			skip_entries = 0;
> -	}
> +	if (argc && kstrtoint(argv[1], 0, &skip_entries))
> +		return KDB_BADINT;
>  
>  	if (argc == 2) {
> -		cpu_file = simple_strtol(argv[2], &cp, 0);
> -		if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
> -		    !cpu_online(cpu_file))
> +		err = kstrtol(argv[2], 0, &cpu_file);
> +		if (err || cpu_file >= NR_CPUS || cpu_file < 0 ||
> +			!cpu_online(cpu_file))
>  			return KDB_BADINT;
>  	} else {
>  		cpu_file = RING_BUFFER_ALL_CPUS;
> -- 
> 2.39.2


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>