[PATCH 5.6 05/23] USB: cdc-acm: restore capability check order

Greg Kroah-Hartman
2020-03-31T09:00:36Z

From: Matthias Reichl <hias@horus.com>

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>

---
drivers/usb/class/cdc-acm.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

--- 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_st

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;