Re: [PATCH v3 2/4] lib/string_helpers.c: protect string_get_size() against blk_size=0

From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	James Bottomley <JBottomley@odin.com>,
	Kees Cook <keescook@chromium.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 2/4] lib/string_helpers.c: protect string_get_size() against blk_size=0
Date: Thu, 29 Oct 2015 23:24:32 +0200	[thread overview]
Message-ID: <CAHp75VfgghsneW+41PEgZPZkXCP-haq+nf5MOLvnqr6DZmSpOw@mail.gmail.com> (raw)
In-Reply-To: <1446136250-11507-3-git-send-email-vkuznets@redhat.com>

On Thu, Oct 29, 2015 at 6:30 PM, Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
> Division by zero happens if blk_size=0 is supplied to string_get_size().
> Add WARN_ON() and set size to 0 to report '0 B'.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> ---
>  lib/string_helpers.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/lib/string_helpers.c b/lib/string_helpers.c
> index f6c27dc..ff3575b 100644
> --- a/lib/string_helpers.c
> +++ b/lib/string_helpers.c
> @@ -50,6 +50,11 @@ void string_get_size(u64 size, u32 blk_size, const enum string_size_units units,
>
>         tmp[0] = '\0';
>         i = 0;
> +
> +       /* Calling string_get_size() with blk_size=0 is wrong! */
> +       if (WARN_ON(!blk_size))
> +               size = 0;
> +
>         if (!size)
>                 goto out;
>
> --
> 2.4.3
>
> --
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-- 
With Best Regards,
Andy Shevchenko