The MITRE CVE dictionary describes this issue as:
The napi_reuse_skb function in net/core/dev.c in the Generic Receive Offload (GRO) implementation in the Linux kernel before 2.6.38 does not reset the values of certain structure members, which might allow remote attackers to cause a denial of service (NULL pointer dereference) via a malformed VLAN frame.
Find out more about CVE-2011-1478 from the
MITRE CVE dictionary dictionary and
This issue did not affect the version of Linux kernel as shipped with Red Hat Enterprise Linux 4 as it did not support Generic Receive Offload (GRO). It has been addressed in Red Hat Enterprise Linux 5, 6, and Red Hat Enterprise MRG via https://rhn.redhat.com/errata/RHSA-2011-0429.html, https://rhn.redhat.com/errata/RHSA-2011-0421.html and https://rhn.redhat.com/errata/RHSA-2011-1253.html.