[NETFILTER]: Fix another crash in ip_nat_pptp

The PPTP NAT helper calculates the offset at which the packet needs
to be mangled as difference between two pointers to the header. With
non-linear skbs however the pointers may point to two seperate buffers
on the stack and the calculation results in a wrong offset beeing
used.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy 2006-01-09 16:44:00 -08:00 committed by David S. Miller
commit 03b9feca89