[PATCH 4.14 122/159] virtio_net: fix return value check in receive_mergeable()

4.14-stable review patch. If anyone has any objections, please let me know. -- From: Yunjian Wang [ Upstream commit 03e9f8a05bce7330bcd9c5cc54c8e42d0fcbf993 ] The function virtqueue_get_buf_ctx() could return NULL, the return value 'buf' need to be

[PATCH 4.14 122/159] virtio_net: fix return value check in receive_mergeable()

4.14-stable review patch. If anyone has any objections, please let me know. -- From: Yunjian Wang [ Upstream commit 03e9f8a05bce7330bcd9c5cc54c8e42d0fcbf993 ] The function virtqueue_get_buf_ctx() could return NULL, the return value 'buf' need to be checked with NULL, not