DEBIAN-CVE-2026-74473

In the Linux kernel, the following vulnerability has been resolved:  vxlan: use pskbnetworkmaypull() in routeshortcircuit()  routeshortcircuit() currently calls pskbmaypull(skb, sizeof(struct iphdr)) (or ipv6hdr), which checks if bytes are available starting from skb->data.  However, in vxlanxmit(), skb->data points to the MAC header, so skbnetworkoffset(skb) is ETHHLEN (14 bytes). Using pskbmaypull(skb, 20) only checks 20 bytes from skb->data (which is 14 bytes MAC header + 6 bytes of IP header), leaving the rest of the IP header potentially un-pulled in non-linear frags. Subsequent dereferences of iphdr(skb)->daddr can read beyond the pulled linear buffer length.  Fix this by using pskbnetworkmaypull(), which adds skbnetwork_offset(skb) to the length check to ensure the full network header is present in the linear buffer.