Patch "net: usb: lan78xx: Limit packet length to skb->len" has been added to the 6.2-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: usb: lan78xx: Limit packet length to skb->len

to the 6.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-usb-lan78xx-limit-packet-length-to-skb-len.patch
and it can be found in the queue-6.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 07910b19444151e2192e6c6dbf0fd4fd1e2bf95a
Author: Szymon Heidrich <szymon.heidrich@xxxxxxxxx>
Date:   Sat Mar 18 10:25:52 2023 +0100

    net: usb: lan78xx: Limit packet length to skb->len
    
    [ Upstream commit 7f247f5a2c18b3f21206cdd51193df4f38e1b9f5 ]
    
    Packet length retrieved from descriptor may be larger than
    the actual socket buffer length. In such case the cloned
    skb passed up the network stack will leak kernel memory contents.
    
    Additionally prevent integer underflow when size is less than
    ETH_FCS_LEN.
    
    Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
    Signed-off-by: Szymon Heidrich <szymon.heidrich@xxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index 068488890d57b..c458c030fadf6 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -3579,13 +3579,29 @@ static int lan78xx_rx(struct lan78xx_net *dev, struct sk_buff *skb,
 		size = (rx_cmd_a & RX_CMD_A_LEN_MASK_);
 		align_count = (4 - ((size + RXW_PADDING) % 4)) % 4;
 
+		if (unlikely(size > skb->len)) {
+			netif_dbg(dev, rx_err, dev->net,
+				  "size err rx_cmd_a=0x%08x\n",
+				  rx_cmd_a);
+			return 0;
+		}
+
 		if (unlikely(rx_cmd_a & RX_CMD_A_RED_)) {
 			netif_dbg(dev, rx_err, dev->net,
 				  "Error rx_cmd_a=0x%08x", rx_cmd_a);
 		} else {
-			u32 frame_len = size - ETH_FCS_LEN;
+			u32 frame_len;
 			struct sk_buff *skb2;
 
+			if (unlikely(size < ETH_FCS_LEN)) {
+				netif_dbg(dev, rx_err, dev->net,
+					  "size err rx_cmd_a=0x%08x\n",
+					  rx_cmd_a);
+				return 0;
+			}
+
+			frame_len = size - ETH_FCS_LEN;
+
 			skb2 = napi_alloc_skb(&dev->napi, frame_len);
 			if (!skb2)
 				return 0;