[PATCH 4.19 070/421] media: dvb_net: avoid speculation from net slot

Greg Kroah-Hartman
2021-07-19T16:09:20Z

From: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

[ Upstream commit abc0226df64dc137b48b911c1fe4319aec5891bb ]

The risk of especulation is actually almost-non-existing here,
as there are very few users of TCP/IP using the DVB stack,
as, this is mainly used with DVB-S/S2 cards, and only by people
that receives TCP/IP from satellite connections, which limits
a lot the number of users of such feature(*).

(*) In thesis, DVB-C cards could also benefit from it, but I'm
yet to see a hardware that supports it.

Yet, fixing it is trivial.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/dvb-core/dvb_net.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/media/dvb-core/dvb_net.c b/drivers/media/dvb-core/dvb_net.c
index 10f78109bb3f..3f154755bbc6 100644
--- a/drivers/media/dvb-core/dvb_net.c
+++ b/drivers/media/dvb-core/dvb_net.c
@@ -56,6 +56,7 @@
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
+#include <linux/nospec.h>
#include <linux/etherdevice.h>
#include <linux/dvb/net.h>
#include <linux/uio.h>
@@ -1473,14 +1474,20 @@ static int dvb_net_do_ioctl(struct file *file,
struct net_device *netdev;
struct dvb_net_priv *priv_data;
struct dvb_net_if *dvbnetif = parg;
+ int if_num = dvbnetif->if_num;

- if (dvbnetif->if_num >= DVB_NET_DEVICES_MAX ||
- !dvbnet->state[dvbnetif->if_num]) {
+ if (if_num >= DVB_NET_DEVICES_MAX) {
ret = -EINVAL;
goto ioctl_error;
}
+ if_num = array_index_nospec(if_num, DVB_NET_DEVICES_MAX);

- netdev = dvbnet->device[dvbnetif->if_num];
+ if (!dvbnet->state[if_num]) {
+ ret = -EINVAL;
+ goto ioctl_error;
+ }
+
+ netdev = dvbnet->device[if_num];

priv_data = netdev_priv(netdev);
dvbnetif->pid=priv_data->pid;
@@ -1533,14 +1540,20 @@ static int dvb_net_do_ioctl(struct file *file,
struct net_device *netdev;
struct dvb_net_priv *priv_data;
struct __dvb_net_if_old *dvbnetif = parg;
+ int if_num = dvbnetif->if_num;
+
+ if (if_num >= DVB_NET_DEVICES_MAX) {
+ ret = -EINVAL;
+ goto ioctl_error;
+ }
+ if_num = array_index_nospec(if_num, DVB_NET_DEVICES_MAX);

- if (dvbnetif->if_num >= DVB_NET_DEVICES_MAX ||
- !dvbnet->state[dvbnetif->if_num]) {
+ if (!dvbnet->state[if_num]) {
ret = -EINVAL;
goto ioctl_error;
}

- netdev = dvbnet->device[dvbnetif->if_num];
+ netdev = dvbnet->device[if_num];

priv_data = netdev_priv(netdev);
dvbnetif->pid=priv_data->pid;
--
2.30.2