4.19-stable review patch. If anyone has any objections, please let me know.
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From: Stefano Brivio sbrivio@redhat.com
[ Upstream commit 7adf3246092f5e87ed0fa610e8088fae416c581f ]
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: f8a1b43b709d ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv6/route.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -210,7 +210,9 @@ struct neighbour *ip6_neigh_lookup(const 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,