pptp: fix stack info leak in pptp_getname()

pptp_getname() only partially initializes the stack variable sa,
particularly only fills the pptp part of the sa_addr union. The code
thereby discloses 16 bytes of kernel stack memory via getsockname().

Fix this by memset(0)'ing the union before.

Cc: Dmitry Kozlov <xeb@mail.ru>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c
index 1aff970be33e..1dc628ffce2b 100644
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c
@@ -506,7 +506,9 @@ static int pptp_getname(struct socket *sock, struct sockaddr *uaddr,
         int len = sizeof(struct sockaddr_pppox);
         struct sockaddr_pppox sp;
 
-        sp.sa_family      = AF_PPPOX;
+        memset(&sp.sa_addr, 0, sizeof(sp.sa_addr));
+
+        sp.sa_family    = AF_PPPOX;
         sp.sa_protocol  = PX_PROTO_PPTP;
         sp.sa_addr.pptp = pppox_sk(sock->sk)->proto.pptp.src_addr;