Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

packet: use consistent hard_header_len in TX_RING send path

tpacket_snd() reads dev->hard_header_len independently for skb allocation and header construction in tpacket_fill_skb(). Concurrent netdevice reconfiguration can therefore make the reserved headroom smaller than the amount later pushed, or make copylen - hard_header_len negative.

Snapshot hard_header_len once before processing ring frames and use it for the frame limit, headroom allocation, copy length, and skb construction. Pass the snapshot to tpacket_fill_skb().

The separate SOCK_DGRAM consistency problem between hard_header_len and header_ops->create is not addressed here.