linux-kernel - [PATCH] ipc: explicitly clear stack memory for shminfo

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Date:	Tue, 16 Nov 2010 11:58:28 -0800
From:	Kees Cook <kees.cook@...onical.com>
To:	linux-kernel@...r.kernel.org
Cc:	Pekka Enberg <penberg@...nel.org>, Joe Perches <joe@...ches.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	"David S. Miller" <davem@...emloft.net>,
	Hugh Dickins <hughd@...gle.com>,
	Manfred Spraul <manfred@...orfullife.com>,
	Vasiliy Kulikov <segooon@...il.com>
Subject: [PATCH] ipc: explicitly clear stack memory for shminfo

This fixes a kernel stack memory contents leak by explicitly clearing
the shminfo structure on the kernel stack before it is populated and
copied back to userspace.

Signed-off-by: Kees Cook <kees.cook@...onical.com>
Acked-by: Pekka Enberg <penberg@...nel.org>
---
 ipc/shm.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/ipc/shm.c b/ipc/shm.c
index 7d3bb22..1d3d41f 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -531,6 +531,7 @@ static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminf
 	    {
 		struct shminfo out;
 
+		memset(&out, 0, sizeof(out));
 		if(in->shmmax > INT_MAX)
 			out.shmmax = INT_MAX;
 		else
-- 
1.7.2.3

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