Re: [PATCH] eeepc-laptop: remove possible use of uninitialized value

Darren Hart
2014-09-04T00:49:59Z

On Thu, Sep 04, 2014 at 12:53:25AM +0200, Frans Klaver wrote:
> In store_sys_acpi, if count equals zero, or parse_arg()s sscanf call
> fails, 'value' remains possibly uninitialized. In that case 'value'
> shouldn't be used to produce the store_sys_acpi()s return value.
>
> Only test the return value of set_acpi() if we can actually call it.
> Return rv otherwise.
>
> Signed-off-by: Frans Klaver <fransklaver@gmail.com>
> ---
> drivers/platform/x86/eeepc-laptop.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c
> index bd533c2..41f12ba 100644
> --- a/drivers/platform/x86/eeepc-laptop.c
> +++ b/drivers/platform/x86/eeepc-laptop.c
> @@ -279,10 +279,10 @@ static ssize_t store_sys_acpi(struct device *dev, int cm,
> int rv, value;
>
> rv = parse_arg(buf, count, &value);
> - if (rv > 0)
> - value = set_acpi(eeepc, cm, value);

That was rather horrible wasn't it? :-)

> - if (value < 0)
> - return -EIO;
> + if (rv > 0) {
> + if (set_acpi(eeepc, cm, value) < 0)
> + return -EIO;

Is there a compelling reason not to propogate the return code of set_acpi?
(ENODEV specifically). I see -EIO in Documentation/filesystems/sysfs.txt, but
it's used by default if the show() pointer is NULL (for example), but otherwise
propogates the error.

Specifically it states:

- show() or store() can always return errors. If a bad value comes
through, be sure to return an error.

Greg, does this need to be -EIO? or is returning someting like ENODEV preferable
if it more accurately reflects the error?

--
Darren Hart
Intel Open Source Technology Center