From 03f384bc0cb8d4a1301d4f5b0baef2d980258383 Mon Sep 17 00:00:00 2001 From: Xiang Mei Date: Mon, 29 Jun 2026 21:51:21 -0700 Subject: [PATCH] net: usb: net1080: validate packet_len before pad-byte access in rx_fixup For an even packet_len, net1080_rx_fixup() reads the pad byte at skb->data[packet_len] before the skb->len != packet_len check further down, and packet_len is only bounded against NC_MAX_PACKET. A malicious NetChip 1080 device can send a short frame advertising a large even packet_len (e.g. 0x4000), so the pad-byte read lands past the end of the skb: BUG: KASAN: slab-out-of-bounds in net1080_rx_fixup Read of size 1 at addr ffff8880106c83c6 by task ksoftirqd/0/14 ... net1080_rx_fixup (drivers/net/usb/net1080.c:384) usbnet_bh (drivers/net/usb/usbnet.c:1589) process_one_work (kernel/workqueue.c:3322) bh_worker (kernel/workqueue.c:3708) tasklet_action (kernel/softirq.c:965) handle_softirqs (kernel/softirq.c:622) ... Reject the frame when packet_len >= skb->len before reading. Fixes: 904813cd8a0b ("[PATCH] USB: usbnet (4/9) module for net1080 cables") Reported-by: Weiming Shi Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Xiang Mei Link: https://patch.msgid.link/20260630045121.1565324-1-xmei5@asu.edu Signed-off-by: Paolo Abeni --- drivers/net/usb/net1080.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/usb/net1080.c b/drivers/net/usb/net1080.c index 5d4a1fd2b524..19f6e1222d93 100644 --- a/drivers/net/usb/net1080.c +++ b/drivers/net/usb/net1080.c @@ -381,7 +381,7 @@ static int net1080_rx_fixup(struct usbnet *dev, struct sk_buff *skb) skb_trim(skb, skb->len - sizeof *trailer); if ((packet_len & 0x01) == 0) { - if (skb->data [packet_len] != PAD_BYTE) { + if (packet_len >= skb->len || skb->data[packet_len] != PAD_BYTE) { dev->net->stats.rx_frame_errors++; netdev_dbg(dev->net, "bad pad\n"); return 0;