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SubjectRe: [PATCH 5/9] staging: panel: check put_user() return value


Willy Tarreau schrieb:
> On Fri, Jul 30, 2010 at 03:08:42PM +0400, Kulikov Vasiliy wrote:
>> diff --git a/drivers/staging/panel/panel.c b/drivers/staging/panel/panel.c
>> index f58da32..57f4946 100644
>> --- a/drivers/staging/panel/panel.c
>> +++ b/drivers/staging/panel/panel.c
>> @@ -1589,25 +1589,30 @@ void lcd_init(void)
>> static ssize_t keypad_read(struct file *file,
>> char *buf, size_t count, loff_t *ppos)
>> {
>> -
>> + int buflen = keypad_buflen;
>> unsigned i = *ppos;
>> char *tmp = buf;
>> + int start = keypad_start;
>>
>> - if (keypad_buflen == 0) {
>> + if (buflen == 0) {
>> if (file->f_flags & O_NONBLOCK)
>> return -EAGAIN;
>>
>> interruptible_sleep_on(&keypad_read_wait);
>> if (signal_pending(current))
>> return -EINTR;
>> + buflen = keypad_buflen;
>> }
>
> Not sure what the intent was here, I think you're re-adjusting
> the buffer's length in case something else was read. But then
> I don't understand why buflen it not simply assigned after the
> if() block.
>
> The rest below looks fine otherwise.
>
>>
>> - for (; count-- > 0 && (keypad_buflen > 0);
>> - ++i, ++tmp, --keypad_buflen) {
>> - put_user(keypad_buffer[keypad_start], tmp);
>> - keypad_start = (keypad_start + 1) % KEYPAD_BUFFER;
>> + for (; count-- > 0 && (buflen > 0);
>> + ++i, ++tmp, --buflen) {
>> + if (put_user(keypad_buffer[start], tmp))
>> + return -EFAULT;
>> + start = (start + 1) % KEYPAD_BUFFER;
>> }
>> *ppos = i;
>> + keypad_buflen = buflen;
>> + keypad_start = start;
>>
>> return tmp - buf;
>> }
>
>

IMHO opinion the for() construct breaks the rule of "no surprise please".
perhaps a while() would improve readability.

just my two cents,
re,
wh






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