• Tommi Rantala's avatar
    sctp: fix dst refcnt leak in sctp_v4_get_dst · 9f02a069
    Tommi Rantala authored
    
    [ Upstream commit 4a31a6b1 ]
    
    Fix dst reference count leak in sctp_v4_get_dst() introduced in commit
    410f0383 ("sctp: add routing output fallback"):
    
    When walking the address_list, successive ip_route_output_key() calls
    may return the same rt->dst with the reference incremented on each call.
    
    The code would not decrement the dst refcount when the dst pointer was
    identical from the previous iteration, causing the dst refcnt leak.
    
    Testcase:
      ip netns add TEST
      ip netns exec TEST ip link set lo up
      ip link add dummy0 type dummy
      ip link add dummy1 type dummy
      ip link add dummy2 type dummy
      ip link set dev dummy0 netns TEST
      ip link set dev dummy1 netns TEST
      ip link set dev dummy2 netns TEST
      ip netns exec TEST ip addr add 192.168.1.1/24 dev dummy0
      ip netns exec TEST ip link set dummy0 up
      ip netns exec TEST ip addr add 192.168.1.2/24 dev dummy1
      ip netns exec TEST ip link set dummy1 up
      ip netns exec TEST ip addr add 192.168.1.3/24 dev dummy2
      ip netns exec TEST ip link set dummy2 up
      ip netns exec TEST sctp_test -H 192.168.1.2 -P 20002 -h 192.168.1.1 -p 20000 -s -B 192.168.1.3
      ip netns del TEST
    
    In 4.4 and 4.9 kernels this results to:
      [  354.179591] unregister_netdevice: waiting for lo to become free. Usage count = 1
      [  364.419674] unregister_netdevice: waiting for lo to become free. Usage count = 1
      [  374.663664] unregister_netdevice: waiting for lo to become free. Usage count = 1
      [  384.903717] unregister_netdevice: waiting for lo to become free. Usage count = 1
      [  395.143724] unregister_netdevice: waiting for lo to become free. Usage count = 1
      [  405.383645] unregister_netdevice: waiting for lo to become free. Usage count = 1
      ...
    
    Fixes: 410f0383 ("sctp: add routing output fallback")
    Fixes: 0ca50d12 ("sctp: fix src address selection if using secondary addresses")
    Signed-off-by: default avatarTommi Rantala <tommi.t.rantala@nokia.com>
    Acked-by: default avatarMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
    Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    9f02a069
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