From 9e56790ad31d72a5a44142af462d047c0c897b29 Mon Sep 17 00:00:00 2001 From: Jesper Juhl Date: Thu, 13 Jan 2011 11:40:11 +0000 Subject: [PATCH] USB CDC NCM: Don't deref NULL in cdc_ncm_rx_fixup() and don't use uninitialized variable. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit skb_clone() dynamically allocates memory and may fail. If it does it returns NULL. This means we'll dereference a NULL pointer in drivers/net/usb/cdc_ncm.c::cdc_ncm_rx_fixup(). As far as I can tell, the proper way to deal with this is simply to goto the error label. Furthermore gcc complains that 'skb' may be used uninitialized: drivers/net/usb/cdc_ncm.c: In function ‘cdc_ncm_rx_fixup’: drivers/net/usb/cdc_ncm.c:922:18: warning: ‘skb’ may be used uninitialized in this function and I believe it is right. On the line where we pr_debug("invalid frame detected (ignored)" ... we are using the local variable 'skb' but nothing has ever been assigned to that variable yet. I believe the correct fix for that is to use 'skb_in' instead. Signed-off-by: Jesper Juhl Signed-off-by: David S. Miller --- drivers/net/usb/cdc_ncm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index 593c104ab199..d776c4a8d3c1 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -1021,13 +1021,15 @@ static int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in) (temp > CDC_NCM_MAX_DATAGRAM_SIZE) || (temp < ETH_HLEN)) { pr_debug("invalid frame detected (ignored)" "offset[%u]=%u, length=%u, skb=%p\n", - x, offset, temp, skb); + x, offset, temp, skb_in); if (!x) goto error; break; } else { skb = skb_clone(skb_in, GFP_ATOMIC); + if (!skb) + goto error; skb->len = temp; skb->data = ((u8 *)skb_in->data) + offset; skb_set_tail_pointer(skb, temp);