[099/118] ax25: fix info leak via msg_name in ax25_recvmsg()

Ben Hutchings
2013-05-10T14:46:24Z

From: Mathias Krause <minipli@googlemail.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@linux-mips.org>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.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;