Description

In the Linux kernel, the following vulnerability has been resolved: ovpn: fix possible use-after-free in ovpn_net_xmit When building the skb_list in ovpn_net_xmit, skb_share_check will free the original skb if it is shared. The current implementation continues to use the stale skb pointer for subsequent operations: - peer lookup, - skb_dst_drop (even though all segments produced by skb_gso_segment will have a dst attached), - ovpn_peer_stats_increment_tx. Fix this by moving the peer lookup and skb_dst_drop before segmentation so that the original skb is still valid when used. Return early if all segments fail skb_share_check and the list ends up empty. Also switch ovpn_peer_stats_increment_tx to use skb_list.next; the next patch fixes the stats logic.

References 3

• git.kernel.org https://git.kernel.org/stable/c/3e4fbcb4e078915367ba5576cd70d76dbc970f95
• git.kernel.org https://git.kernel.org/stable/c/442915c96a9bff1c7080e2aedabb1c03faa28d81
• git.kernel.org https://git.kernel.org/stable/c/a5ec7baa44ea3a1d6aa0ca31c0ad82edf9affe41

Remediation