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USB CDC NCM: Don't deref NULL in cdc_ncm_rx_fixup() and don't use uninitialized variable.

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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 <jj@chaosbits.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jesper Juhl 2011-01-13 11:40:11 +00:00 committed by David S. Miller
parent e84f885ebf
commit 9e56790ad3
1 changed files with 3 additions and 1 deletions
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4
drivers/net/usb/cdc_ncm.c
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@ -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);