Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   "Andrea Parri (Microsoft)" <parri.andrea@gmail.com>
To:     linux-kernel@vger.kernel.org
Cc:     "K . Y . Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, linux-hyperv@vger.kernel.org,
        Michael Kelley <mikelley@microsoft.com>,
        Juan Vazquez <juvazq@microsoft.com>,
        Saruhan Karademir <skarade@microsoft.com>,
        "Andrea Parri (Microsoft)" <parri.andrea@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org
Subject: [PATCH] hv_netvsc: Validate number of allocated sub-channels
Date:   Wed, 18 Nov 2020 16:33:10 +0100
Message-Id: <20201118153310.112404-1-parri.andrea@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
---
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