linux-kernel - [PATCH 3.16 251/305] batman-adv: Fix memory leak on tt add with invalid vlan

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Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "David S. Miller" <davem@...emloft.net>,
	"Sven Eckelmann" <sven@...fation.org>
Subject: [PATCH 3.16 251/305] batman-adv: Fix memory leak on tt add with
 invalid vlan

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

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

From: Sven Eckelmann <sven@...fation.org>

commit fd7dec25a18f495e50d2040398fd263836ff3b28 upstream.

The object tt_local is allocated with kmalloc and not initialized when the
function batadv_tt_local_add checks for the vlan. But this function can
only cleanup the object when the (not yet initialized) reference counter of
the object is 1. This is unlikely and thus the object would leak when the
vlan could not be found.

Instead the uninitialized object tt_local has to be freed manually and the
pointer has to set to NULL to avoid calling the function which would try to
decrement the reference counter of the not existing object.

CID: 1316518
Fixes: 354136bcc3c4 ("batman-adv: fix kernel crash due to missing NULL checks")
Signed-off-by: Sven Eckelmann <sven@...fation.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/batman-adv/translation-table.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -577,8 +577,11 @@ bool batadv_tt_local_add(struct net_devi
 	/* increase the refcounter of the related vlan */
 	vlan = batadv_softif_vlan_get(bat_priv, vid);
 	if (WARN(!vlan, "adding TT local entry %pM to non-existent VLAN %d",
-		 addr, BATADV_PRINT_VID(vid)))
+		 addr, BATADV_PRINT_VID(vid))) {
+		kfree(tt_local);
+		tt_local = NULL;
 		goto out;
+	}

 	batadv_dbg(BATADV_DBG_TT, bat_priv,
 		   "Creating new local tt entry: %pM (vid: %d, ttvn: %d)\n",