From 7f247f5a2c18b3f21206cdd51193df4f38e1b9f5 Mon Sep 17 00:00:00 2001 From: Szymon Heidrich Date: Sat, 18 Mar 2023 10:25:52 +0100 Subject: net: usb: lan78xx: Limit packet length to skb->len 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 Signed-off-by: David S. Miller --- drivers/net/usb/lan78xx.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c index 068488890d57..c458c030fadf 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; -- cgit