releases/4.9.94/net-cdc_ncm-fix-tx-zero-padding.patch

From foo@baz Mon Apr  9 17:09:24 CEST 2018
From: Jim Baxter <jim_baxter@mentor.com>
Date: Mon, 8 May 2017 13:49:57 +0100
Subject: net: cdc_ncm: Fix TX zero padding

From: Jim Baxter <jim_baxter@mentor.com>


[ Upstream commit aeca3a77b1e0ed06a095933b89c86aed007383eb ]

The zero padding that is added to NTB's does
not zero the memory correctly.
This is because the skb_put modifies the value
of skb_out->len which results in the memset
command not setting any memory to zero as
(ctx->tx_max - skb_out->len) == 0.

I have resolved this by storing the size of
the memory to be zeroed before the skb_put
and using this in the memset call.

Signed-off-by: Jim Baxter <jim_baxter@mentor.com>
Reviewed-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/usb/cdc_ncm.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -1118,6 +1118,7 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev
 	u16 n = 0, index, ndplen;
 	u8 ready2send = 0;
 	u32 delayed_ndp_size;
+	size_t padding_count;
 
 	/* When our NDP gets written in cdc_ncm_ndp(), then skb_out->len gets updated
 	 * accordingly. Otherwise, we should check here.
@@ -1274,11 +1275,13 @@ cdc_ncm_fill_tx_frame(struct usbnet *dev
 	 * a ZLP after full sized NTBs.
 	 */
 	if (!(dev->driver_info->flags & FLAG_SEND_ZLP) &&
-	    skb_out->len > ctx->min_tx_pkt)
-		memset(skb_put(skb_out, ctx->tx_max - skb_out->len), 0,
-		       ctx->tx_max - skb_out->len);
-	else if (skb_out->len < ctx->tx_max && (skb_out->len % dev->maxpacket) == 0)
+	    skb_out->len > ctx->min_tx_pkt) {
+		padding_count = ctx->tx_max - skb_out->len;
+		memset(skb_put(skb_out, padding_count), 0, padding_count);
+	} else if (skb_out->len < ctx->tx_max &&
+		   (skb_out->len % dev->maxpacket) == 0) {
 		*skb_put(skb_out, 1) = 0;	/* force short packet */
+	}
 
 	/* set final frame length */
 	nth16 = (struct usb_cdc_ncm_nth16 *)skb_out->data;