Subject: [PATCH AUTOSEL 4.14 40/66] hv_netvsc: Validate number of allocated sub-channels

From: Sasha Levin <[email-masked]>
Date: Tue, 22 Dec 2020 21:22:26 -0500

From: "Andrea Parri (Microsoft)" <[email-masked]>

[ Upstream commit 206ad34d52a2f1205c84d08c12fc116aad0eb407 ]

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 <[email-masked]>
Signed-off-by: Andrea Parri (Microsoft) <[email-masked]>
Reviewed-by: Haiyang Zhang <[email-masked]>
Acked-by: Jakub Kicinski <[email-masked]>
Cc: "David S. Miller" <[email-masked]>
Cc: Jakub Kicinski <[email-masked]>
Cc: [email-masked]
Link: https://lore.kernel.org/r/[email-masked]
Signed-off-by: Wei Liu <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 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 aa0bbffe49005..1db34b7a423ef 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1100,6 +1100,11 @@ int rndis_set_subchannel(struct net_device *ndev, struct netvsc_device *nvdev)
 		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;
 
-- 
2.27.0