[PATCH net-next] rndis_host: add overflow check in rndis_rx_fixup()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Griffin Kroah-Hartman <griffin@kroah.com>

Add an overflow check to ensure that data_offset + data_len + 8 does not
wrap, which would enable an OOB read of the USB data buffer.

Assisted-by: gkh_clanker_1000
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Shaoxu Liu <shaoxul@foxmail.com>
Signed-off-by: Griffin Kroah-Hartman <griffin@kroah.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/usb/rndis_host.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/rndis_host.c b/drivers/net/usb/rndis_host.c
index 5e39d05a2d7b..37d4865f5c5e 100644
--- a/drivers/net/usb/rndis_host.c
+++ b/drivers/net/usb/rndis_host.c
@@ -14,6 +14,7 @@
 #include <linux/usb/cdc.h>
 #include <linux/usb/usbnet.h>
 #include <linux/usb/rndis_host.h>
+#include <linux/overflow.h>
 
 
 /*
@@ -506,6 +507,7 @@ int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 		struct rndis_data_hdr	*hdr = (void *)skb->data;
 		struct sk_buff		*skb2;
 		u32			msg_type, msg_len, data_offset, data_len;
+		u32			overflow_check;
 
 		msg_type = le32_to_cpu(hdr->msg_type);
 		msg_len = le32_to_cpu(hdr->msg_len);
@@ -514,7 +516,9 @@ int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 
 		/* don't choke if we see oob, per-packet data, etc */
 		if (unlikely(msg_type != RNDIS_MSG_PACKET || skb->len < msg_len
-				|| (data_offset + data_len + 8) > msg_len)) {
+				|| (data_offset + data_len + 8) > msg_len
+				|| check_add_overflow(data_offset, data_len, &overflow_check)
+				|| check_add_overflow(overflow_check, 8, &overflow_check))) {
 			dev->net->stats.rx_frame_errors++;
 			netdev_dbg(dev->net, "bad rndis message %d/%d/%d/%d, len %d\n",
 				   le32_to_cpu(hdr->msg_type),
-- 
2.55.0