On Wed, Feb 18, 2015 at 1:14 PM, Alexey Dobriyan <adobri...@gmail.com> wrote:
> 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
I think this patch won't break any existing module using this function.
because this function sets KSTRTOX_OVERFLOW as error status.
which is checked by calling function to determine whether value is correct
or not.
If this flag is set we can simply discard the parsed value.
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