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 <[email protected]> Fixes: f8a1b43b709d ("net/ipv6: Create a neigh_lookup for FIB entries") Signed-off-by: Stefano Brivio <[email protected]> --- net/ipv6/route.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index a94e0b02a8ac..40b225f87d5e 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -210,7 +210,9 @@ struct neighbour *ip6_neigh_lookup(const struct in6_addr *gw, n = __ipv6_neigh_lookup(dev, daddr); if (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, -- 2.19.2
