linux-kernel - [PATCH 4.4 033/268] kconfig: Fix expr_free() E

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Message-Id: <20180528100205.827852300@linuxfoundation.org>
Date:   Mon, 28 May 2018 12:00:07 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ulf Magnusson <ulfalizer@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.4 033/268] kconfig: Fix expr_free() E_NOT leak

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ulf Magnusson <ulfalizer@...il.com>

[ Upstream commit 5b1374b3b3c2fc4f63a398adfa446fb8eff791a4 ]

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>
Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 scripts/kconfig/expr.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- 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: