linux-kernel - [PATCH] net: core: scm: fix information leak to userland

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Date:	Sat, 30 Oct 2010 18:26:35 +0400
From:	Vasiliy Kulikov <segooon@...il.com>
To:	kernel-janitors@...r.kernel.org
Cc:	"David S. Miller" <davem@...emloft.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Tejun Heo <tj@...nel.org>,
	"Serge E. Hallyn" <serge@...lyn.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] net: core: scm: fix information leak to userland

Structure cmsghdr is copied to userland with padding bytes
unitialized on architectures where __kernel_size_t is unsigned long.
It leads to leaking of contents of kernel stack memory.

Signed-off-by: Vasiliy Kulikov <segooon@...il.com>
---
 Compile tested.

 net/core/scm.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/net/core/scm.c b/net/core/scm.c
index 413cab8..a4a9b70 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -233,6 +233,7 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
 		msg->msg_flags |= MSG_CTRUNC;
 		cmlen = msg->msg_controllen;
 	}
+	memset(&cmhdr, 0, sizeof(cmhdr));
 	cmhdr.cmsg_level = level;
 	cmhdr.cmsg_type = type;
 	cmhdr.cmsg_len = cmlen;
-- 
1.7.0.4

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