linux-kernel - [099/118] ax25: fix info leak via msg_name in ax25

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Date:	Fri, 10 May 2013 14:39:41 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "David S. Miller" <davem@...emloft.net>,
	"Ralf Baechle" <ralf@...ux-mips.org>,
	"Mathias Krause" <minipli@...glemail.com>
Subject: [099/118] ax25: fix info leak via msg_name in ax25_recvmsg()

3.2.45-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Mathias Krause <minipli@...glemail.com>

[ Upstream commit ef3313e84acbf349caecae942ab3ab731471f1a1 ]

When msg_namelen is non-zero the sockaddr info gets filled out, as
requested, but the code fails to initialize the padding bytes of struct
sockaddr_ax25 inserted by the compiler for alignment. Additionally the
msg_namelen value is updated to sizeof(struct full_sockaddr_ax25) but is
not always filled up to this size.

Both issues lead to the fact that the code will leak uninitialized
kernel stack bytes in net/socket.c.

Fix both issues by initializing the memory with memset(0).

Cc: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Mathias Krause <minipli@...glemail.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/ax25/af_ax25.c | 1 +
 1 file changed, 1 insertion(+)

--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1641,6 +1641,7 @@ static int ax25_recvmsg(struct kiocb *io
 		ax25_address src;
 		const unsigned char *mac = skb_mac_header(skb);
 
+		memset(sax, 0, sizeof(struct full_sockaddr_ax25));
 		ax25_addr_parse(mac + 1, skb->data - mac - 1, &src, NULL,
 				&digi, NULL, NULL);
 		sax->sax25_family = AF_AX25;

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