[PATCH v2] net: ax25: fix information leak to userland

[PATCH v2] net: ax25: fix information leak to userland

[Vasiliy Kulikov]

Sometimes ax25_getname() doesn't initialize all members of fsa_digipeater
field of fsa struct, also the struct has padding bytes between
sax25_call and sax25_ndigis fields.  This structure is then copied to
userland.  It leads to leaking of contents of kernel stack memory.

Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
---
 Compile tested.

 net/ax25/af_ax25.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index 26eaebf..bb86d29 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1392,6 +1392,7 @@ static int ax25_getname(struct socket *sock, struct sockaddr *uaddr,
 	ax25_cb *ax25;
 	int err = 0;
 
+	memset(fsa, 0, sizeof(fsa));
 	lock_sock(sk);
 	ax25 = ax25_sk(sk);
 
@@ -1403,7 +1404,6 @@ static int ax25_getname(struct socket *sock, struct sockaddr *uaddr,
 
 		fsa->fsa_ax25.sax25_family = AF_AX25;
 		fsa->fsa_ax25.sax25_call   = ax25->dest_addr;
-		fsa->fsa_ax25.sax25_ndigis = 0;
 
 		if (ax25->digipeat != NULL) {
 			ndigi = ax25->digipeat->ndigi;
-- 
1.7.0.4

Re: [PATCH v2] net: ax25: fix information leak to userland

[David Miller]

From: Vasiliy Kulikov <segooon@gmail.com>
Date: Wed, 10 Nov 2010 21:12:36 +0300

> Sometimes ax25_getname() doesn't initialize all members of fsa_digipeater
> field of fsa struct, also the struct has padding bytes between
> sax25_call and sax25_ndigis fields.  This structure is then copied to
> userland.  It leads to leaking of contents of kernel stack memory.
> 
> Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>

Looks good to me, applied.

Thanks!