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-Tag: v4.19.95~39
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=a64d7894b4614e6507f108f402d854868969a9c1;p=thirdparty%2Fkernel%2Fstable.git

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

[ Upstream commit 272a72103012862e3a24ea06635253ead0b6e808 ]

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: Sasha Levin <sashal@kernel.org>
---

diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index e1a39e90841d8..7e38070ee523b 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -252,6 +252,13 @@ 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) {