From: Jiaxun Yang <jiaxun.yang@flygoat.com>
Date: Tue, 11 Apr 2023 11:14:26 +0000 (+0100)
Subject: MIPS: fw: Allow firmware to pass a empty env
X-Git-Tag: v6.1.28~555
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a6b54af407873227caef6262e992f5422cdcb6ae;p=users%2Fdwmw2%2Flinux.git

MIPS: fw: Allow firmware to pass a empty env

commit ee1809ed7bc456a72dc8410b475b73021a3a68d5 upstream.

fw_getenv will use env entry to determine style of env,
however it is legal for firmware to just pass a empty list.

Check if first entry exist before running strchr to avoid
null pointer dereference.

Cc: stable@vger.kernel.org
Link: https://github.com/clbr/n64bootloader/issues/5
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/mips/fw/lib/cmdline.c b/arch/mips/fw/lib/cmdline.c
index f24cbb4a39b50..892765b742bbc 100644
--- a/arch/mips/fw/lib/cmdline.c
+++ b/arch/mips/fw/lib/cmdline.c
@@ -53,7 +53,7 @@ char *fw_getenv(char *envname)
 {
 	char *result = NULL;
 
-	if (_fw_envp != NULL) {
+	if (_fw_envp != NULL && fw_envp(0) != NULL) {
 		/*
 		 * Return a pointer to the given environment variable.
 		 * YAMON uses "name", "value" pairs, while U-Boot uses