[PATCH 150/173] net: ax25: fix information leak to userland

[Willy Tarreau]

2.6.27.59-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Vasiliy Kulikov <segooon@xxxxxxxxx>

commit fe10ae53384e48c51996941b7720ee16995cbcb7 upstream.

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@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Moritz Muehlenhoff <jmm@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 net/ax25/af_ax25.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1391,6 +1391,7 @@ static int ax25_getname(struct socket *s
 	ax25_cb *ax25;
 	int err = 0;
 
+	memset(fsa, 0, sizeof(fsa));
 	lock_sock(sk);
 	ax25 = ax25_sk(sk);
 
@@ -1402,7 +1403,6 @@ static int ax25_getname(struct socket *s
 
 		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;


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