Vulnerability: net/tipc/socket.c in the Linux kernel before 3.9-rc7 does not initialize a certain data structure and a certain length variable, which allows local users to obtain sensitive information from kernel stack memory via a crafted recvmsg or recvfrom system call.
Vulnerability ID: CVE-2013-3235
CWE: CWE-200
Severity score: 6.9
Project: https://github.com/torvalds/linux
Published: 2013-04-22
File: net/tipc/socket.c
Commit message: tipc: fix info leaks via msg_name in recv_msg/recv_stream

The code in set_orig_addr() does not initialize all of the members of
struct sockaddr_tipc when filling the sockaddr info -- namely the union
is only partly filled. This will make recv_msg() and recv_stream() --
the only users of this function -- leak kernel stack memory as the
msg_name member is a local variable in net/socket.c.

Additionally to that both recv_msg() and recv_stream() fail to update
the msg_namelen member to 0 while otherwise returning with 0, i.e.
"success". This is the case for, e.g., non-blocking sockets. This will
lead to a 128 byte kernel stack leak in net/socket.c.

Fix the first issue by initializing the memory of the union with
memset(0). Fix the second one by setting msg_namelen to 0 early as it
will be updated later if we're going to fill the msg_name member.

Cc: Jon Maloy <jon.maloy@ericsson.com>
Cc: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit author: Mathias Krause

Vulnerable version (before fix):
 static void set_orig_addr(struct msghdr *m, struct tipc_msg *msg) 	if (addr) { 		addr->family = AF_TIPC; 		addr->addrtype = TIPC_ADDR_ID; 		addr->addr.id.ref = msg_origport(msg); 		addr->addr.id.node = msg_orignode(msg); 		addr->addr.name.domain = 0;	/* could leave uninitialized */ static int recv_msg(struct kiocb *iocb, struct socket *sock, 		goto exit; 	}  	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); restart:  static int recv_stream(struct kiocb *iocb, struct socket *sock, 		goto exit; 	}  	target = sock_rcvlowat(sk, flags & MSG_WAITALL, buf_len); 	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); 

Fixed version (after fix):
 static void set_orig_addr(struct msghdr *m, struct tipc_msg *msg) 	if (addr) { 		addr->family = AF_TIPC; 		addr->addrtype = TIPC_ADDR_ID; 		memset(&addr->addr, 0, sizeof(addr->addr)); 		addr->addr.id.ref = msg_origport(msg); 		addr->addr.id.node = msg_orignode(msg); 		addr->addr.name.domain = 0;	/* could leave uninitialized */ static int recv_msg(struct kiocb *iocb, struct socket *sock, 		goto exit; 	}  	/* will be updated in set_orig_addr() if needed */ 	m->msg_namelen = 0;  	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); restart:  static int recv_stream(struct kiocb *iocb, struct socket *sock, 		goto exit; 	}  	/* will be updated in set_orig_addr() if needed */ 	m->msg_namelen = 0;  	target = sock_rcvlowat(sk, flags & MSG_WAITALL, buf_len); 	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); 

Patch:
patch: @@ -790,6 +790,7 @@ static void set_orig_addr(struct msghdr *m, struct tipc_msg *msg)
 	if (addr) {
 		addr->family = AF_TIPC;
 		addr->addrtype = TIPC_ADDR_ID;
+		memset(&addr->addr, 0, sizeof(addr->addr));
 		addr->addr.id.ref = msg_origport(msg);
 		addr->addr.id.node = msg_orignode(msg);
 		addr->addr.name.domain = 0;	/* could leave uninitialized */
@@ -904,6 +905,9 @@ static int recv_msg(struct kiocb *iocb, struct socket *sock,
 		goto exit;
 	}
 
+	/* will be updated in set_orig_addr() if needed */
+	m->msg_namelen = 0;
+
 	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 restart:
 
@@ -1013,6 +1017,9 @@ static int recv_stream(struct kiocb *iocb, struct socket *sock,
 		goto exit;
 	}
 
+	/* will be updated in set_orig_addr() if needed */
+	m->msg_namelen = 0;
+
 	target = sock_rcvlowat(sk, flags & MSG_WAITALL, buf_len);
 	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
path: net/tipc/socket.c