On Tue, Feb 17, 2015 at 04:17:24PM -0800, Andrew Morton wrote:
> ?
>
> Begin forwarded message:
>
> Date: Mon, 16 Feb 2015 10:48:50 -0800
> From: Anshul Garg <aksgarg1...@gmail.com>
> To: linux-kernel@vger.kernel.org
> Cc: aksgarg1...@gmail.com, anshu...@samsung.com, torva...@linux-foundation.org
> Subject: [PATCH] lib/kstrtox.c Stop parsing integer on overflow
>
>
> From: Anshul Garg <aksgarg1...@gmail.com>
>
> While converting string representation to integer
> break the loop if overflow is detected.
>
> Signed-off-by: Anshul Garg <aksgarg1...@gmail.com>
> ---
> lib/kstrtox.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/lib/kstrtox.c b/lib/kstrtox.c
> index ec8da78..6f30209 100644
> --- a/lib/kstrtox.c
> +++ b/lib/kstrtox.c
> @@ -70,8 +70,10 @@ unsigned int _parse_integer(const char *s, unsigned int
> base, unsigned long long
> * it in the max base we support (16)
> */
> if (unlikely(res & (~0ull << 60))) {
> - if (res > div_u64(ULLONG_MAX - val, base))
> + if (res > div_u64(ULLONG_MAX - val, base)) {
> overflow = 1;
> + break;
> + }
> }
> res = res * base + val;
> rv++;
The _notion_ of a patch is OK if you want EVERY simple_strtoull() call
to stop parsing past overflow right now. It SHOULD have done so from day 1,
but it doesn't do that.
When I wrote kstrto*() code I deliberatedly didn't break this bug
because of the sheer number of call sites.
If you are OK with changing bug-for-bug compatibility,
then patch simply need to delete overflow detection code.
Alexey
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