Hi, > From: Dan Carpenter [mailto:dan.carpenter@xxxxxxxxxx] > Sent: Friday, December 25, 2015 3:16 AM > Subject: Re: [patch 2/2] ACPI / debugger: copy_to_user doesn't return errors > > On Thu, Dec 24, 2015 at 08:39:06AM +0100, Julia Lawall wrote: > > On Thu, 24 Dec 2015, Dan Carpenter wrote: > > > > > The copy_to/from_user() functions don't return error codes, they return > > > the number of bytes remaining. We had intended to return -EFUALT here. > > > We actually have already checked access_ok() in an earlier function so > > > I don't think these functions will fail but let's fix it anyway. > > > > > > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > > > > > > diff --git a/drivers/acpi/acpi_dbg.c b/drivers/acpi/acpi_dbg.c > > > index f2c92ab..2a1777b 100644 > > > --- a/drivers/acpi/acpi_dbg.c > > > +++ b/drivers/acpi/acpi_dbg.c > > > @@ -592,9 +592,10 @@ static int acpi_aml_read_user(char __user *buf, > int len) > > > smp_rmb(); > > > p = &crc->buf[crc->tail]; > > > n = min(len, circ_count_to_end(crc)); > > > - ret = copy_to_user(buf, p, n); > > > - if (IS_ERR_VALUE(ret)) > > > > I'm not familiar with IS_ERR_VALUE. Is it to allow functions that > > return unsigned values to also return negative error codes? > > Yes, but here it is used as a substitue for checking if (ret < 0) or if > (ret >= 0). I would have prefered to open code it. Also I prefer > if (ret) for when the value is either zero or negative error codes but > here we have standardized on IS_ERR_VALUE(ret) for everything. [Lv Zheng] This patch looks correct. It's good for me to know the rule for copy_to/from_user(). Thanks for pointing out. Thanks and best regards -Lv > > regards, > dan carpenter -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
