diff mbox series

[SRU,F,1/1] CDC-NCM: avoid overflow in sanity checking

Message ID 20241024220625.31584-2-bethany.jamison@canonical.com
State New
Headers show
Series [SRU,F,1/1] CDC-NCM: avoid overflow in sanity checking | expand

Commit Message

Bethany Jamison Oct. 24, 2024, 10:06 p.m. UTC 
From: Oliver Neukum <oneukum@suse.com>

commit 8d2b1a1ec9f559d30b724877da4ce592edc41fdc upstream.

A broken device may give an extreme offset like 0xFFF0
and a reasonable length for a fragment. In the sanity
check as formulated now, this will create an integer
overflow, defeating the sanity check. Both offset
and offset + len need to be checked in such a manner
that no overflow can occur.
And those quantities should be unsigned.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 69560efa001397ebb8dc1c3e6a3ce00302bb9f7f linux-5.10.y)
CVE-2022-48938
Signed-off-by: Bethany Jamison <bethany.jamison@canonical.com>
---
 drivers/net/usb/cdc_ncm.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 4824385fe2c79..c86340fede082 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -1707,10 +1707,10 @@  int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in)
 {
 	struct sk_buff *skb;
 	struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
-	int len;
+	unsigned int len;
 	int nframes;
 	int x;
-	int offset;
+	unsigned int offset;
 	union {
 		struct usb_cdc_ncm_ndp16 *ndp16;
 		struct usb_cdc_ncm_ndp32 *ndp32;
@@ -1782,8 +1782,8 @@  int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in)
 			break;
 		}
 
-		/* sanity checking */
-		if (((offset + len) > skb_in->len) ||
+		/* sanity checking - watch out for integer wrap*/
+		if ((offset > skb_in->len) || (len > skb_in->len - offset) ||
 				(len > ctx->rx_max) || (len < ETH_HLEN)) {
 			netif_dbg(dev, rx_err, dev->net,
 				  "invalid frame detected (ignored) offset[%u]=%u, length=%u, skb=%p\n",