diff mbox series

[net-next,v4,2/4] usbnet: ipheth: transmit URBs without trailing padding

Message ID 20230607135702.32679-2-forst@pen.gy (mailing list archive)
State Accepted
Commit 3e65efcca87a9bb5f3b864e0a43d167bc0a8688c
Headers show
Series [net-next,v4,1/4] usbnet: ipheth: fix risk of NULL pointer deallocation | expand

Commit Message

Foster Snowhill June 7, 2023, 1:57 p.m. UTC 
The behaviour of the official iOS tethering driver on macOS is to not
transmit any trailing padding at the end of URBs. This is applicable
to both NCM and legacy modes, including older devices.

Adapt the driver to not include trailing padding in TX URBs, matching
the behaviour of the official macOS driver.

Signed-off-by: Foster Snowhill <forst@pen.gy>
Tested-by: Georgi Valkov <gvalkov@gmail.com>
---
Tested by Georgi Valkov on iPhone 3G (iOS 4.2.1), iPhone 4s (iOS 8.4),
iPhone 7 Plus (iOS 15.7.6).

Tested by Foster Snowhill on iPhone Xs Max (iOS 16.5).

Additionally both Georgi and Foster did USB traffic captures with the
devices above on macOS 13.4, this confirmed the macOS driver behaviour.

v4:
  No code change.
  Factored out from "usbnet: ipheth: add CDC NCM support".
v3: n/a
  Part of https://lore.kernel.org/netdev/20230527130309.34090-2-forst@pen.gy/
v2: n/a
  Part of https://lore.kernel.org/netdev/20230525194255.4516-2-forst@pen.gy/
v1: n/a
  Part of https://lore.kernel.org/netdev/20230516210127.35841-1-forst@pen.gy/
---
 drivers/net/usb/ipheth.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c
index 8875a3d0e..dd809e247 100644
--- a/drivers/net/usb/ipheth.c
+++ b/drivers/net/usb/ipheth.c
@@ -373,12 +373,10 @@  static netdev_tx_t ipheth_tx(struct sk_buff *skb, struct net_device *net)
 	}
 
 	memcpy(dev->tx_buf, skb->data, skb->len);
-	if (skb->len < IPHETH_BUF_SIZE)
-		memset(dev->tx_buf + skb->len, 0, IPHETH_BUF_SIZE - skb->len);
 
 	usb_fill_bulk_urb(dev->tx_urb, udev,
 			  usb_sndbulkpipe(udev, dev->bulk_out),
-			  dev->tx_buf, IPHETH_BUF_SIZE,
+			  dev->tx_buf, skb->len,
 			  ipheth_sndbulk_callback,
 			  dev);
 	dev->tx_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;