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

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Message-ID: <CAD=FV=XpK0T-oPi2Q6-9jELFseSsvgkFtRuXP1LXK6PbV_MwCg@mail.gmail.com>
Date:   Tue, 5 Dec 2023 13:41:57 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Yuran Pereira <yuran.pereira@...mail.com>
Cc:     kgdb-bugreport@...ts.sourceforge.net,
        linux-trace-kernel@...r.kernel.org, jason.wessel@...driver.com,
        daniel.thompson@...aro.org, rostedt@...dmis.org,
        mhiramat@...nel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH 2/2] trace: kdb: Replace simple_strtoul with kstrtoul in kdb_ftdump

Hi,

On Sun, Nov 19, 2023 at 4:10 PM Yuran Pereira <yuran.pereira@...mail.com> 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
>
> Signed-off-by: Yuran Pereira <yuran.pereira@...mail.com>
> ---
>  kernel/trace/trace_kdb.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
> index 59857a1ee44c..3891f885e4a6 100644
> --- a/kernel/trace/trace_kdb.c
> +++ b/kernel/trace/trace_kdb.c
> @@ -96,23 +96,21 @@ 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)
> +       if (argc)
> +               if (kstrtoint(argv[1], 0, &skip_entries))
>                         skip_entries = 0;
> -       }

Similar nit about braces as in patch #1. tl;dr is change the above to:

if (argc && kstrtoint(argv[1], 0, &skip_entries))
  skip_entries = 0;


>
>         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))

nit: why did you change the indentation for "!cpu_online(cpu_file))"?
It seemed better before.

With nits fixed:

Reviewed-by: Douglas Anderson <dianders@...omium.org>