linux-kernel - [PATCH 2/3] kconfig: Fix expr_free() E

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Message-Id: <1507484146-23617-3-git-send-email-ulfalizer@gmail.com>
Date:   Sun,  8 Oct 2017 19:35:45 +0200
From:   Ulf Magnusson <ulfalizer@...il.com>
To:     yann.morin.1998@...e.fr, linux-kbuild@...r.kernel.org
Cc:     sam@...nborg.org, zippel@...ux-m68k.org, nicolas.pitre@...aro.org,
        michal.lkml@...kovi.net, dirk@...ders.net,
        yamada.masahiro@...ionext.com, lacombar@...il.com,
        walch.martin@....de, JBeulich@...e.com,
        linux-kernel@...r.kernel.org, Ulf Magnusson <ulfalizer@...il.com>
Subject: [PATCH 2/3] kconfig: Fix expr_free() E_NOT leak

Only the E_NOT operand and not the E_NOT node itself was freed, due to
accidentally returning too early in expr_free(). Outline of leak:

	switch (e->type) {
	...
	case E_NOT:
		expr_free(e->left.expr);
		return;
	...
	}
	*Never reached, 'e' leaked*
	free(e);

Fix by changing the 'return' to a 'break'.

Summary from Valgrind on 'menuconfig' (ARCH=x86) before the fix:

	LEAK SUMMARY:
	   definitely lost: 44,448 bytes in 1,852 blocks
	   ...

Summary after the fix:

	LEAK SUMMARY:
	   definitely lost: 1,608 bytes in 67 blocks
	   ...

Signed-off-by: Ulf Magnusson <ulfalizer@...il.com>
---
 scripts/kconfig/expr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index cbf4996..ed29bad 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -113,7 +113,7 @@ void expr_free(struct expr *e)
 		break;
 	case E_NOT:
 		expr_free(e->left.expr);
-		return;
+		break;
 	case E_EQUAL:
 	case E_GEQ:
 	case E_GTH:
-- 
2.7.4