libbpf: Ensure umem pointer is non-NULL before dereferencing

Calls to xsk_socket__create dereference the umem to access the
fill_save and comp_save pointers. Make sure the umem is non-NULL
before doing this.

Fixes: 2f6324a3937f ("libbpf: Support shared umems between queues and devices")
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20210331061218.1647-2-ciara.loftus@intel.com

diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index 526fc35..443b0cf 100644 (file)
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -1019,6 +1019,9 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
                       struct xsk_ring_cons *rx, struct xsk_ring_prod *tx,
                       const struct xsk_socket_config *usr_config)
 {
+       if (!umem)
+               return -EFAULT;
+
        return xsk_socket__create_shared(xsk_ptr, ifname, queue_id, umem,
                                         rx, tx, umem->fill_save,
                                         umem->comp_save, usr_config);