linux-kernel - Re: [PATCH 2/2] reboot: fix parsing of reboot cpu number

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Date:   Fri, 16 Oct 2020 15:46:19 -0400
From:   Pavel Tatashin <pasha.tatashin@...een.com>
To:     Matteo Croce <mcroce@...ux.microsoft.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Petr Mladek <pmladek@...e.com>, Arnd Bergmann <arnd@...db.de>,
        Mike Rapoport <rppt@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Robin Holt <robinmholt@...il.com>,
        Fabian Frederick <fabf@...net.be>,
        stable <stable@...r.kernel.org>
Subject: Re: [PATCH 2/2] reboot: fix parsing of reboot cpu number

On Fri, Oct 16, 2020 at 2:09 PM Matteo Croce <mcroce@...ux.microsoft.com> wrote:
>
> From: Matteo Croce <mcroce@...rosoft.com>
>
> The kernel cmdline reboot= argument allows to specify the CPU used
> for rebooting, with the syntax `s####` among the other flags, e.g.
>
>   reboot=soft,s4
>   reboot=warm,s31,force
>
> In the early days the parsing was done with simple_strtoul(), later
> deprecated in favor of the safer kstrtoint() which handles overflow.
>
> But kstrtoint() returns -EINVAL if there are non-digit characters
> in a string, so if this flag is not the last given, it's silently
> ignored as well as the subsequent ones.
>
> To fix it, revert the usage of simple_strtoul(), which is no longer
> deprecated, and restore the old behaviour.
>
> While at it, merge two identical code blocks into one.
>
> Fixes: 616feab75397 ("kernel/reboot.c: convert simple_strtoul to kstrtoint")
> Signed-off-by: Matteo Croce <mcroce@...rosoft.com>

Reviewed-by: Pavel Tatashin <pasha.tatashin@...een.com>