[PATCH] hv_netvsc: Validate number of allocated sub-channels

[Andrea Parri (Microsoft)]

Lack of validation could lead to out-of-bound reads and information
leaks (cf. usage of nvdev->chan_table[]).  Check that the number of
allocated sub-channels fits into the expected range.

Suggested-by: Saruhan Karademir <skarade@xxxxxxxxxxxxx>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
---
Based on hyperv-next.

 drivers/net/hyperv/rndis_filter.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 3835d9bea1005..c5a709f67870f 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1226,6 +1226,11 @@ int rndis_set_subchannel(struct net_device *ndev,
 		return -EIO;
 	}
 
+	/* Check that number of allocated sub channel is within the expected range */
+	if (init_packet->msg.v5_msg.subchn_comp.num_subchannels > nvdev->num_chn - 1) {
+		netdev_err(ndev, "invalid number of allocated sub channel\n");
+		return -EINVAL;
+	}
 	nvdev->num_chn = 1 +
 		init_packet->msg.v5_msg.subchn_comp.num_subchannels;
 
-- 
2.25.1