From 75efe7dc996ddb9835590b1a8970f19b5c4b1ade Mon Sep 17 00:00:00 2001
From: Dimitri John Ledkov <xnox@ubuntu.com>
Date: Wed, 21 Apr 2021 12:42:01 +0100
Subject: [PATCH] cmd: pxe_utils: sysboot: fix crash if either board or soc are
 not set.

If the environment does not have "soc" or "board" set, and fdtdir
option is specified in extlinux.conf, the bootloader will crash whilst
dereferencing a null pointer. Add a guard against null soc or
board. Fixes a crash of qemu-riscv64_smode configuration, which does
not have CONFIG_SYS_SOC defined.

Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
---
 cmd/pxe_utils.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/cmd/pxe_utils.c b/cmd/pxe_utils.c
index 71c5af4c25..9a30629e26 100644
--- a/cmd/pxe_utils.c
+++ b/cmd/pxe_utils.c
@@ -587,6 +587,14 @@ static int label_boot(struct cmd_tbl *cmdtp, struct pxe_label *label)
 				f2 = "-";
 				f3 = env_get("board");
 				f4 = ".dtb";
+				if (!f1) {
+					f1 = "";
+					f2 = "";
+				}
+				if (!f3) {
+					f2 = "";
+					f3 = "";
+				}
 			}
 
 			len = strlen(label->fdtdir);