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.
https://bugzilla.redhat.com/show_bug.cgi?id=691270
http://www.vmware.com/security/advisories/VMSA-2011-0012.html
http://www.securityfocus.com/archive/1/520102/100/0/threaded
http://securityreason.com/securityalert/8480
http://secunia.com/advisories/46397