USB: serial: keyspan_pda: fix modem-status error handling

commit 01b3cdfca263a17554f7b249d20a247b2a751521 upstream.

Fix broken modem-status error handling which could lead to bits of slab
data leaking to user space.

Fixes: 3b36a8fd6777 ("usb: fix uninitialized variable warning in keyspan_pda")
Cc: stable <stable@vger.kernel.org>     # 2.6.27
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index d2dab2a..d17f787 100644 (file)
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -373,8 +373,10 @@ static int keyspan_pda_get_modem_info(struct usb_serial *serial,
                             3, /* get pins */
                             USB_TYPE_VENDOR|USB_RECIP_INTERFACE|USB_DIR_IN,
                             0, 0, data, 1, 2000);
-       if (rc >= 0)
+       if (rc == 1)
                *value = *data;
+       else if (rc >= 0)
+               rc = -EIO;
 
        kfree(data);
        return rc;