netdev - [PATCH 02/16] ax25: fix info leak via msg_name in ax25

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Message-Id: <1365335522-29931-3-git-send-email-minipli@googlemail.com>
Date:	Sun,  7 Apr 2013 13:51:48 +0200
From:	Mathias Krause <minipli@...glemail.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org,
	Allan Stephens <allan.stephens@...driver.com>,
	Aloisio Almeida Jr <aloisio.almeida@...nbossa.org>,
	Andy King <acking@...are.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Dmitry Torokhov <dtor@...are.com>,
	George Zhang <georgezhang@...are.com>,
	Gustavo Padovan <gustavo@...ovan.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	Jon Maloy <jon.maloy@...csson.com>,
	Lauro Ramos Venancio <lauro.venancio@...nbossa.org>,
	Marcel Holtmann <marcel@...tmann.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Samuel Ortiz <samuel@...tiz.org>,
	Sjur Braendeland <sjur.brandeland@...ricsson.com>,
	Ursula Braun <ursula.braun@...ibm.com>,
	Brad Spengler <spender@...ecurity.net>,
	Mathias Krause <minipli@...glemail.com>
Subject: [PATCH 02/16] ax25: fix info leak via msg_name in ax25_recvmsg()

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>
---
 net/ax25/af_ax25.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index 7b11f8b..e277e38 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1642,6 +1642,7 @@ static int ax25_recvmsg(struct kiocb *iocb, struct socket *sock,
 		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;
-- 
1.7.10.4

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