From: Thomas Hebb <tommyhebb@gmail.com>
Date: Mon, 9 Dec 2019 08:19:17 +0000 (-0800)
Subject: kconfig: don't crash on NULL expressions in expr_eq()
X-Git-Url: https://jxself.org/git/?p=carl9170fw.git;a=commitdiff_plain;h=26ed147bb322afcf071ef4e5eb595480221430dc

kconfig: don't crash on NULL expressions in expr_eq()

NULL expressions are taken to always be true, as implemented by the
expr_is_yes() macro and by several other functions in expr.c. As such,
they ought to be valid inputs to expr_eq(), which compares two
expressions.

Signed-off-by: Thomas Hebb <tommyhebb@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
---

diff --git a/config/expr.c b/config/expr.c
index 77ffff3..9f1de58 100644
--- a/config/expr.c
+++ b/config/expr.c
@@ -254,6 +254,13 @@ static int expr_eq(struct expr *e1, struct expr *e2)
 {
 	int res, old_count;
 
+	/*
+	 * A NULL expr is taken to be yes, but there's also a different way to
+	 * represent yes. expr_is_yes() checks for either representation.
+	 */
+	if (!e1 || !e2)
+		return expr_is_yes(e1) && expr_is_yes(e2);
+
 	if (e1->type != e2->type)
 		return 0;
 	switch (e1->type) {