linux-kernel - [PATCH AUTOSEL 5.2 019/249] media: dvb: usb: fix use after free in dvb_usb_device

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Message-Id: <20190715134655.4076-19-sashal@kernel.org>
Date:   Mon, 15 Jul 2019 09:43:04 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Oliver Neukum <oneukum@...e.com>,
        syzbot+26ec41e9f788b3eba396@...kaller.appspotmail.com,
        Sean Young <sean@...s.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Sasha Levin <sashal@...nel.org>, linux-media@...r.kernel.org
Subject: [PATCH AUTOSEL 5.2 019/249] media: dvb: usb: fix use after free in dvb_usb_device_exit

From: Oliver Neukum <oneukum@...e.com>

[ Upstream commit 6cf97230cd5f36b7665099083272595c55d72be7 ]

dvb_usb_device_exit() frees and uses the device name in that order.
Fix by storing the name in a buffer before freeing it.

Signed-off-by: Oliver Neukum <oneukum@...e.com>
Reported-by: syzbot+26ec41e9f788b3eba396@...kaller.appspotmail.com
Signed-off-by: Sean Young <sean@...s.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/usb/dvb-usb/dvb-usb-init.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/dvb-usb-init.c b/drivers/media/usb/dvb-usb/dvb-usb-init.c
index e97f6edc98de..65f2b1a20ca1 100644
--- a/drivers/media/usb/dvb-usb/dvb-usb-init.c
+++ b/drivers/media/usb/dvb-usb/dvb-usb-init.c
@@ -284,12 +284,15 @@ EXPORT_SYMBOL(dvb_usb_device_init);
 void dvb_usb_device_exit(struct usb_interface *intf)
 {
 	struct dvb_usb_device *d = usb_get_intfdata(intf);
-	const char *name = "generic DVB-USB module";
+	const char *default_name = "generic DVB-USB module";
+	char name[40];
 
 	usb_set_intfdata(intf, NULL);
 	if (d != NULL && d->desc != NULL) {
-		name = d->desc->name;
+		strscpy(name, d->desc->name, sizeof(name));
 		dvb_usb_exit(d);
+	} else {
+		strscpy(name, default_name, sizeof(name));
 	}
 	info("%s successfully deinitialized and disconnected.", name);
 
-- 
2.20.1