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由 Eric Dumazet 提交于
Multicast dst are not cached. They carry DST_NOCACHE. As mentioned in commit f8864972 ("ipv4: fix dst race in sk_dst_get()"), these dst need special care before caching them into a socket. Caching them is allowed only if their refcnt was not 0, ie we must use atomic_inc_not_zero() Also, we must use READ_ONCE() to fetch sk->sk_rx_dst, as mentioned in commit d0c294c5 ("tcp: prevent fetching dst twice in early demux code") Fixes: 421b3885 ("udp: ipv4: Add udp early demux") Tested-by: NGregory Hoggarth <Gregory.Hoggarth@alliedtelesis.co.nz> Signed-off-by: NEric Dumazet <edumazet@google.com> Reported-by: NGregory Hoggarth <Gregory.Hoggarth@alliedtelesis.co.nz> Reported-by: NAlex Gartrell <agartrell@fb.com> Cc: Michal Kubeček <mkubecek@suse.cz> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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