Re: [PATCH] Typecasting required for comparing unlike datatypes

[Harsh Bora <harsh@linux.vnet.ibm.com>]

On 12/10/2010 01:48 PM, KAMEZAWA Hiroyuki wrote:
> On Wed,  8 Dec 2010 18:25:00 +0530
> Harsh Prateek Bora<harsh@linux.vnet.ibm.com>  wrote:
>
>> The existing code causes the if condition to pass when it should fail
>> on a *64-bit kernel* because of implicit data type conversions. It can
>> be observed by passing pos = -1 and count = some positive number.
>> This results in function returning EOVERFLOW instead of EINVAL.
>>
>> With this patch, the function returns EINVAL when pos is -1 and count
>> is a positive number. This can be tested by calling sendfile with
>> offset = -1 and count = some positive number on a 64-bit kernel.
>>
>> Signed-off-by: Harsh Prateek Bora<harsh@linux.vnet.ibm.com>
>
> Acked-by: KAMEZAWA Hiroyuki<kamezawa.hiroyu@jp.fujitsu.com>
>
> I'm sorry for annoying you.
>
Oh, but I am not annoyed, .. Thanks for the ack though ! :)

>> ---
>>   fs/read_write.c |    2 +-
>>   1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/read_write.c b/fs/read_write.c
>> index 431a0ed..a8eabd4 100644
>> --- a/fs/read_write.c
>> +++ b/fs/read_write.c
>> @@ -38,7 +38,7 @@ __negative_fpos_check(struct file *file, loff_t pos, size_t count)
>>   	 * pos or pos+count is negative here, check overflow.
>>   	 * too big "count" will be caught in rw_verify_area().
>>   	 */
>> -	if ((pos<  0)&&  (pos + count<  pos))
>> +	if ((pos<  0)&&  ( (loff_t) (pos + count)<  pos))
>>   		return -EOVERFLOW;
>>   	if (file->f_mode&  FMODE_UNSIGNED_OFFSET)
>>   		return 0;
>> --
>> 1.7.1.1
>>
>>
>