[NEIGH] Fix timer leak in neigh_changeaddr (49636bb1) · Commits · 戴 / test

neigh_changeaddr attempts to delete neighbour timers without setting nud_state. This doesn't work because the timer may have already fired when we acquire the write lock in neigh_changeaddr. The result is that the timer may keep firing for quite a while until the entry reaches NEIGH_FAILED. It should be setting the nud_state straight away so that if the timer has already fired it can simply exit once we relinquish the lock. In fact, this whole function is simply duplicating the logic in neigh_ifdown which in turn is already doing the right thing when it comes to deleting timers and setting nud_state. So all we have to do is take that code out and put it into a common function and make both neigh_changeaddr and neigh_ifdown call it. Signed-off-by:

Herbert Xu <herbert@gondor.apana.org.au>

net/core/neighbour.c

+13 −30

Original line number	Diff line number	Diff line
		@@ -175,39 +175,10 @@ static void pneigh_queue_purge(struct sk_buff_head *list)
		}
		}

		void neigh_changeaddr(struct neigh_table tbl, struct net_device dev)
		{
		int i;

		write_lock_bh(&tbl->lock);

		for (i=0; i <= tbl->hash_mask; i++) {
		struct neighbour n, *np;

		np = &tbl->hash_buckets[i];
		while ((n = *np) != NULL) {
		if (dev && n->dev != dev) {
		np = &n->next;
		continue;
		}
		*np = n->next;
		write_lock_bh(&n->lock);
		n->dead = 1;
		neigh_del_timer(n);
		write_unlock_bh(&n->lock);
		neigh_release(n);
		}
		}

		write_unlock_bh(&tbl->lock);
		}

		int neigh_ifdown(struct neigh_table tbl, struct net_device dev)
		static void neigh_flush_dev(struct neigh_table tbl, struct net_device dev)
		{
		int i;

		write_lock_bh(&tbl->lock);

		for (i = 0; i <= tbl->hash_mask; i++) {
		struct neighbour n, *np = &tbl->hash_buckets[i];

		@@ -243,7 +214,19 @@ int neigh_ifdown(struct neigh_table tbl, struct net_device dev)
		neigh_release(n);
		}
		}
		}

		void neigh_changeaddr(struct neigh_table tbl, struct net_device dev)
		{
		write_lock_bh(&tbl->lock);
		neigh_flush_dev(tbl, dev);
		write_unlock_bh(&tbl->lock);
		}

		int neigh_ifdown(struct neigh_table tbl, struct net_device dev)
		{
		write_lock_bh(&tbl->lock);
		neigh_flush_dev(tbl, dev);
		pneigh_ifdown(tbl, dev);
		write_unlock_bh(&tbl->lock);

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