[U-Boot] [PATCH] fdt: Check if the FDT address is configured

[Marek Vasut]

In case the "fdt addr" command wasn't ran yet and any other "fdt"
subcommand was issued, the system crashed due to NULL pointer being
used.

This is caused by "fdt addr" command setting up a pointer to the
FDT memory location. Prior issuing "fdt addr", the pointer is NULL
so calling any other subcommands crashed the u-boot.

Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Simon Glass <sjg at chromium.org>
---
 common/cmd_fdt.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

Note: Damn, I'm falling asleep already :-( I hope the text above at
      least makes sense though.

diff --git a/common/cmd_fdt.c b/common/cmd_fdt.c
index 9a5c53e..e2225c4 100644
--- a/common/cmd_fdt.c
+++ b/common/cmd_fdt.c
@@ -114,10 +114,21 @@ int do_fdt (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 			}
 		}
 
+		return CMD_RET_SUCCESS;
+	}
+
+	if (!working_fdt) {
+		puts(
+			"No FDT memory address configured. Please configure\n"
+			"the FDT address via \"fdt addr <address>\" command.\n"
+			"Aborting!\n");
+		return CMD_RET_FAILURE;
+	}
+
 	/*
 	 * Move the working_fdt
 	 */
-	} else if (strncmp(argv[1], "mo", 2) == 0) {
+	if (strncmp(argv[1], "mo", 2) == 0) {
 		struct fdt_header *newaddr;
 		int  len;
 		int  err;
-- 
1.7.10.4