[PATCH 4.18 027/135] net: qualcomm: rmnet: Skip processing loopback packets

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sean Tranchetti <stranche@xxxxxxxxxxxxxx>

[ Upstream commit a07f388e2cde2be74b263f85df6f672fea0305a1 ]

RMNET RX handler was processing invalid packets that were
originally sent on the real device and were looped back via
dev_loopback_xmit(). This was detected using syzkaller.

Fixes: ceed73a2cf4a ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation")
Signed-off-by: Sean Tranchetti <stranche@xxxxxxxxxxxxxx>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
@@ -189,6 +189,9 @@ rx_handler_result_t rmnet_rx_handler(str
 	if (!skb)
 		goto done;
 
+	if (skb->pkt_type == PACKET_LOOPBACK)
+		return RX_HANDLER_PASS;
+
 	dev = skb->dev;
 	port = rmnet_get_port(dev);