nvme-fabrics: Use scnprintf() for avoiding potential buffer overflow

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/host/fabrics.c

@@ -105,14 +105,14 @@ int nvmf_get_address(struct nvme_ctrl *ctrl, char *buf, int size)
 	int len = 0;
 
 	if (ctrl->opts->mask & NVMF_OPT_TRADDR)
-		len += snprintf(buf, size, "traddr=%s", ctrl->opts->traddr);
+		len += scnprintf(buf, size, "traddr=%s", ctrl->opts->traddr);
 	if (ctrl->opts->mask & NVMF_OPT_TRSVCID)
-		len += snprintf(buf + len, size - len, "%strsvcid=%s",
+		len += scnprintf(buf + len, size - len, "%strsvcid=%s",
 				(len) ? "," : "", ctrl->opts->trsvcid);
 	if (ctrl->opts->mask & NVMF_OPT_HOST_TRADDR)
-		len += snprintf(buf + len, size - len, "%shost_traddr=%s",
+		len += scnprintf(buf + len, size - len, "%shost_traddr=%s",
 				(len) ? "," : "", ctrl->opts->host_traddr);
-	len += snprintf(buf + len, size - len, "\n");
+	len += scnprintf(buf + len, size - len, "\n");
 
 	return len;
 }