Standard UDP receive path does not use skb->destructor. But skmsg layer does use it, since it calls skb_set_owner_sk_safe() from udp_read_skb(). This then triggers this warning in skb_attempt_defer_free(): DEBUG_NET_WARN_ON_ONCE(skb->destructor); We must call skb_orphan() to fix this issue. Fixes: 6471658dc66c ("udp: use skb_attempt_defer_free()") Reported-by: syzbot+3e68572cf2286ce5ebe9@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/695b83bd.050a0220.1c9965.002b.GAE@google.com/T/#u Signed-off-by: Eric Dumazet --- net/ipv4/udp.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index ffe074cb5865..ee63af0ef42c 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1851,6 +1851,7 @@ void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len) sk_peek_offset_bwd(sk, len); if (!skb_shared(skb)) { + skb_orphan(skb); skb_attempt_defer_free(skb); return; } -- 2.52.0.351.gbe84eed79e-goog