tcp: dont handle MTU reduction on LISTEN socket
When an ICMP ICMP_FRAG_NEEDED (or ICMPV6_PKT_TOOBIG) message finds a LISTEN socket, and this socket is currently owned by the user, we set TCP_MTU_REDUCED_DEFERRED flag in listener tsq_flags. This is bad because if we clone the parent before it had a chance to clear the flag, the child inherits the tsq_flags value, and next tcp_release_cb() on the child will decrement sk_refcnt. Result is that we might free a live TCP socket, as reported by Dormando. IPv4: Attempt to release TCP socket in state 1 Fix this issue by testing sk_state against TCP_LISTEN early, so that we set TCP_MTU_REDUCED_DEFERRED on appropriate sockets (not a LISTEN one) This bug was introduced in commit 563d34d0 (tcp: dont drop MTU reduction indications) Reported-by: Ndormando <dormando@rydia.net> Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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