netdev - [PATCH V1 3/3] asix: Fix small memory leak in ax88772

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Date:   Mon, 7 Aug 2017 09:50:16 +0100
From:   Dean Jenkins <Dean_Jenkins@...tor.com>
To:     <netdev@...r.kernel.org>, David Miller <davem@...emloft.net>,
        Dean Jenkins <Dean_Jenkins@...tor.com>
CC:     <linux-usb@...r.kernel.org>
Subject: [PATCH V1 3/3] asix: Fix small memory leak in ax88772_unbind()

When Ethernet frames span mulitple URBs, the netdev buffer memory
pointed to by the asix_rx_fixup_info structure remains allocated
during the time gap between the 2 executions of asix_rx_fixup_internal().

This means that if ax88772_unbind() is called within this time
gap to free the memory of the parent private data structure then
a memory leak of the part filled netdev buffer memory will occur.

Therefore, create a new function asix_rx_fixup_common_free() to
free the memory of the netdev buffer and add a call to
asix_rx_fixup_common_free() from inside ax88772_unbind().

Consequently when an unbind occurs part way through receiving
an Ethernet frame, the netdev buffer memory that is holding part
of the received Ethernet frame will now be freed.

Signed-off-by: Dean Jenkins <Dean_Jenkins@...tor.com>
---
 drivers/net/usb/asix.h         |  1 +
 drivers/net/usb/asix_common.c  | 15 +++++++++++++++
 drivers/net/usb/asix_devices.c |  1 +
 3 files changed, 17 insertions(+)

diff --git a/drivers/net/usb/asix.h b/drivers/net/usb/asix.h
index d109242..9a4171b 100644
--- a/drivers/net/usb/asix.h
+++ b/drivers/net/usb/asix.h
@@ -209,6 +209,7 @@ void asix_write_cmd_async(struct usbnet *dev, u8 cmd, u16 value,
 int asix_rx_fixup_internal(struct usbnet *dev, struct sk_buff *skb,
 			   struct asix_rx_fixup_info *rx);
 int asix_rx_fixup_common(struct usbnet *dev, struct sk_buff *skb);
+void asix_rx_fixup_common_free(struct asix_common_private *dp);
 
 struct sk_buff *asix_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
 			      gfp_t flags);
diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
index fda74f3..522d290 100644
--- a/drivers/net/usb/asix_common.c
+++ b/drivers/net/usb/asix_common.c
@@ -210,6 +210,21 @@ int asix_rx_fixup_common(struct usbnet *dev, struct sk_buff *skb)
 	return asix_rx_fixup_internal(dev, skb, rx);
 }
 
+void asix_rx_fixup_common_free(struct asix_common_private *dp)
+{
+	struct asix_rx_fixup_info *rx;
+
+	if (!dp)
+		return;
+
+	rx = &dp->rx_fixup_info;
+
+	if (rx->ax_skb) {
+		kfree_skb(rx->ax_skb);
+		rx->ax_skb = NULL;
+	}
+}
+
 struct sk_buff *asix_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
 			      gfp_t flags)
 {
diff --git a/drivers/net/usb/asix_devices.c b/drivers/net/usb/asix_devices.c
index a3aa0a2..b2ff88e 100644
--- a/drivers/net/usb/asix_devices.c
+++ b/drivers/net/usb/asix_devices.c
@@ -764,6 +764,7 @@ static int ax88772_bind(struct usbnet *dev, struct usb_interface *intf)
 
 static void ax88772_unbind(struct usbnet *dev, struct usb_interface *intf)
 {
+	asix_rx_fixup_common_free(dev->driver_priv);
 	kfree(dev->driver_priv);
 }
 
-- 
2.7.4