From: Oliver Neukum <oneukum@xxxxxxxx>
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@xxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/usb/cdc_ncm.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -1702,10 +1702,10 @@ int cdc_ncm_rx_fixup(struct usbnet *dev,
{
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;
@@ -1777,8 +1777,8 @@ next_ndp:
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",
