USB: cdc-acm: restore capability check order

commit 62d65bdd9d05158aa2547f8ef72375535f3bc6e3 upstream.

commit b401f8c4f492c ("USB: cdc-acm: fix rounding error in TIOCSSERIAL")
introduced a regression by changing the order of capability and close
settings change checks. When running with CAP_SYS_ADMIN setting the
close settings to the values already set resulted in -EOPNOTSUPP.

Fix this by changing the check order back to how it was before.

Fixes: b401f8c4f492c ("USB: cdc-acm: fix rounding error in TIOCSSERIAL")
Cc: Anthony Mallet <anthony.mallet@laas.fr>
Cc: stable <stable@vger.kernel.org>
Cc: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Matthias Reichl <hias@horus.com>
Link: https://lore.kernel.org/r/20200327150350.3657-1-hias@horus.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 47f09a6..84d6f7d 100644 (file)
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -923,16 +923,16 @@ static int set_serial_info(struct tty_struct *tty, struct serial_struct *ss)
 
        mutex_lock(&acm->port.mutex);
 
-       if ((ss->close_delay != old_close_delay) ||
-            (ss->closing_wait != old_closing_wait)) {
-               if (!capable(CAP_SYS_ADMIN))
+       if (!capable(CAP_SYS_ADMIN)) {
+               if ((ss->close_delay != old_close_delay) ||
+                   (ss->closing_wait != old_closing_wait))
                        retval = -EPERM;
-               else {
-                       acm->port.close_delay  = close_delay;
-                       acm->port.closing_wait = closing_wait;
-               }
-       } else
-               retval = -EOPNOTSUPP;
+               else
+                       retval = -EOPNOTSUPP;
+       } else {
+               acm->port.close_delay  = close_delay;
+               acm->port.closing_wait = closing_wait;
+       }
 
        mutex_unlock(&acm->port.mutex);
        return retval;