From 429fa68b58cefb9aa9de27e4089637298b46b757 Mon Sep 17 00:00:00 2001
From: Foster Snowhill <forst@pen.gy>
Date: Sun, 26 Jan 2025 00:54:04 +0100
Subject: [PATCH] usbnet: ipheth: check that DPE points past NCM header
By definition, a DPE points at the start of a network frame/datagram.
Thus it makes no sense for it to point at anything that's part of the
NCM header. It is not a security issue, but merely an indication of
a malformed DPE.
Enforce that all DPEs point at the data portion of the URB, past the
NCM header.
Fixes: a2d274c62e44 ("usbnet: ipheth: add CDC NCM support")
Cc: stable@vger.kernel.org
Signed-off-by: Foster Snowhill <forst@pen.gy>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
drivers/net/usb/ipheth.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c
index 45daae234cb85..1ff5f7076ad53 100644
--- a/drivers/net/usb/ipheth.c
+++ b/drivers/net/usb/ipheth.c
@@ -242,7 +242,8 @@ static int ipheth_rcvbulk_callback_ncm(struct urb *urb)
dpe = ncm0->dpe16;
while (le16_to_cpu(dpe->wDatagramIndex) != 0 &&
le16_to_cpu(dpe->wDatagramLength) != 0) {
- if (le16_to_cpu(dpe->wDatagramIndex) >= urb->actual_length ||
+ if (le16_to_cpu(dpe->wDatagramIndex) < IPHETH_NCM_HEADER_SIZE ||
+ le16_to_cpu(dpe->wDatagramIndex) >= urb->actual_length ||
le16_to_cpu(dpe->wDatagramLength) > urb->actual_length -
le16_to_cpu(dpe->wDatagramIndex)) {
dev->net->stats.rx_length_errors++;
--
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