[PATCH 3.16 126/131] irda: Fix memory leak caused by repeated binds of irda socket

[Ben Hutchings]

3.16.59-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Tyler Hicks <tyhicks@xxxxxxxxxxxxx>

The irda_bind() function allocates memory for self->ias_obj without
checking to see if the socket is already bound. A userspace process
could repeatedly bind the socket, have each new object added into the
LM-IAS database, and lose the reference to the old object assigned to
the socket to exhaust memory resources. This patch errors out of the
bind operation when self->ias_obj is already assigned.

CVE-2018-6554

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxx>
Reviewed-by: Seth Arnold <seth.arnold@xxxxxxxxxxxxx>
Reviewed-by: Stefan Bader <stefan.bader@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/irda/af_irda.c | 7 +++++++
 1 file changed, 7 insertions(+)

--- a/net/irda/af_irda.c
+++ b/net/irda/af_irda.c
@@ -786,6 +786,13 @@ static int irda_bind(struct socket *sock
 		return -EINVAL;
 
 	lock_sock(sk);
+
+	/* Ensure that the socket is not already bound */
+	if (self->ias_obj) {
+		err = -EINVAL;
+		goto out;
+	}
+
 #ifdef CONFIG_IRDA_ULTRA
 	/* Special care for Ultra sockets */
 	if ((sk->sk_type == SOCK_DGRAM) &&