net: bridge: fix a bug on using a neighbour cache entry without checking its state

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[ Upstream commit 4c84edc11b ]

When handling DNAT'ed packets on a bridge device, the neighbour cache entry
from lookup was used without checking its state. It means that a cache entry
in the NUD_STALE state will be used directly instead of entering the NUD_DELAY
state to confirm the reachability of the neighbor.

This problem becomes worse after commit 2724680bce ("neigh: Keep neighbour
cache entries if number of them is small enough."), since all neighbour cache
entries in the NUD_STALE state will be kept in the neighbour table as long as
the number of cache entries does not exceed the value specified in gc_thresh1.

This commit validates the state of a neighbour cache entry before using
the entry.

Signed-off-by: JianJhen Chen <kchen@synology.com>
Reviewed-by: JinLin Chen <jlchen@synology.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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JianJhen Chen 2019-01-06 11:28:13 +08:00 • committed by Greg Kroah-Hartman

parent ac6a4d97a7

commit 50265bcad4

1 changed files with 1 additions and 1 deletions

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net/bridge/br_netfilter_hooks.c

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