[PATCH 5.10 048/188] libbpf: Ensure umem pointer is non-NULL before dereferencing

[Greg Kroah-Hartman]

From: Ciara Loftus <ciara.loftus@xxxxxxxxx>

commit df662016310aa4475d7986fd726af45c8fe4f362 upstream.

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@xxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Acked-by: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210331061218.1647-2-ciara.loftus@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 tools/lib/bpf/xsk.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -870,6 +870,9 @@ int xsk_socket__create(struct xsk_socket
 		       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);