Commit 7adf3246 authored Jan 02, 2019 by Stefano Brivio Committed by David S. Miller Jan 02, 2019

ipv6: route: Fix return value of ip6_neigh_lookup() on neigh_create() error



In ip6_neigh_lookup(), we must not return errors coming from
neigh_create(): if creation of a neighbour entry fails, the lookup should
return NULL, in the same way as it's done in __neigh_lookup().

Otherwise, callers legitimately checking for a non-NULL return value of
the lookup function might dereference an invalid pointer.

For instance, on neighbour table overflow, ndisc_router_discovery()
crashes ndisc_update() by passing ERR_PTR(-ENOBUFS) as 'neigh' argument.

Reported-by: Jianlin Shi <jishi@redhat.com>
Fixes: f8a1b43b ("net/ipv6: Create a neigh_lookup for FIB entries")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 202700e3

net/ipv6/route.c

+3 −1

Original line number	Original line	Diff line number	Diff line
	@@ -210,7 +210,9 @@ struct neighbour ip6_neigh_lookup(const struct in6_addr gw,
	n = __ipv6_neigh_lookup(dev, daddr);		n = __ipv6_neigh_lookup(dev, daddr);
	if (n)		if (n)
	return n;		return n;
	return neigh_create(&nd_tbl, daddr, dev);
			n = neigh_create(&nd_tbl, daddr, dev);
			return IS_ERR(n) ? NULL : n;
	}		}

	static struct neighbour ip6_dst_neigh_lookup(const struct dst_entry dst,		static struct neighbour ip6_dst_neigh_lookup(const struct dst_entry dst,