[PATCH AUTOSEL 5.4 132/187] kconfig: don't crash on NULL expressions in expr_eq()

Sasha Levin
2019-12-27T17:43:38Z

From: Thomas Hebb <tommyhebb@gmail.com>

[ 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>
---
scripts/kconfig/expr.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index 77ffff3a053c..9f1de58e9f0c 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/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) {
--
2.20.1