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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Anthony Mallet <anthony.mallet@laas.fr>,
        Oliver Neukum <oneukum@suse.com>,
        Matthias Reichl <hias@horus.com>
Subject: [PATCH 5.5 152/170] USB: cdc-acm: restore capability check order
Date:   Tue, 31 Mar 2020 10:59:26 +0200
Message-Id: <20200331085439.279687524@linuxfoundation.org>
In-Reply-To: <20200331085423.990189598@linuxfoundation.org>
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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;