- flags = p[0];
- if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
- if (flags&(GRE_VERSION|GRE_ROUTING))
- return;
- if (flags&GRE_KEY) {
- grehlen += 4;
- if (flags&GRE_CSUM)
- grehlen += 4;
- }
+ if (!pskb_may_pull(skb, offset + grehlen))
+ return;
+ greh = (const struct gre_base_hdr *)(skb->data + offset);
+ flags = greh->flags;
+ if (flags & (GRE_VERSION | GRE_ROUTING))
+ return;
+ if (flags & GRE_CSUM)
+ grehlen += 4;
+ if (flags & GRE_KEY) {
+ key_off = grehlen + offset;
+ grehlen += 4;