On Mon, Jan 11, 2021 at 02:09:04PM -0800, trix@xxxxxxxxxx wrote:
> From: Tom Rix <trix@xxxxxxxxxx>
>
> clang static analysis reports this problem
>
> mos7720.c:352:2: warning: Undefined or garbage value returned to caller
> return d;
> ^~~~~~~~
>
> In the parport_mos7715_read_data()'s call to read_mos_reg(), 'd' is
> only set after the alloc block.
>
> buf = kmalloc(1, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
>
> Although the problem is reported in parport_most7715_read_data(),
> none of the callee's of read_mos_reg() check the return status.
>
> So move the clearing of data to before the malloc.
>
> Fixes: 0d130367abf5 ("USB: serial: mos7720: fix control-message error handling")
> Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
> ---
> drivers/usb/serial/mos7720.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
> index 41ee2984a0df..23e8162c768b 100644
> --- a/drivers/usb/serial/mos7720.c
> +++ b/drivers/usb/serial/mos7720.c
> @@ -214,6 +214,7 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
> u8 *buf;
> int status;
>
> + *data = 0;
> buf = kmalloc(1, GFP_KERNEL);
> if (!buf)
> return -ENOMEM;
I added a clearing of the buffer to this error path instead to avoid the
redundant assignment for every call due to something which will
basically never happen.
> @@ -227,7 +228,6 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
> "mos7720: usb_control_msg() failed: %d\n", status);
> if (status >= 0)
> status = -EIO;
> - *data = 0;
> }
>
> kfree(buf);
Johan
