ovpn: fix possible use-after-free in ovpn_net_xmit

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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.

Fixes: 08857b5ec5 ("ovpn: implement basic TX path (UDP)")
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>

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Ralf Lici 2026-01-30 18:32:49 +01:00 • committed by Antonio Quartulli

parent 93686c472e

commit a5ec7baa44

1 changed files with 31 additions and 21 deletions

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54

drivers/net/ovpn/io.c

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