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

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Message-ID: <CAD=FV=X+sGVF91WFDpB9cdXboCnL1NX6nZ4z2qE_ctYqZ0sNkw@mail.gmail.com>
Date: Fri, 25 Oct 2024 15:31:34 -0700
From: Doug Anderson <dianders@...omium.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, 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

Hi,

On Mon, Oct 21, 2024 at 2:17 PM 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
>
> Signed-off-by: Yuran Pereira <yuran.pereira@...mail.com>
> Signed-off-by: Nir Lichtman <nir@...htman.org>

I have the same comments as patch #1 about authorship and noting what
you changed.


> ---
>  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))

FWIW, this is still changing the indentation of the second line in a
way that makes it worse list like v1 did [1]. :-P The "!" in "!cpu_"
should line up right under the "e" in "err".

That's a pretty tiny nit, so I'm OK with:

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

When sending v3 you'd want to keep Masami's Acked-by tag and my
Reviewed-by tag. They should go just above your Signed-off-by tag.