[PATCH 4.8 31/33] batman-adv: Check for alloc errors when preparing TT local data

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

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

From: Sven Eckelmann <sven@xxxxxxxxxxxxx>

commit c2d0f48a13e53b4747704c9e692f5e765e52041a upstream.

batadv_tt_prepare_tvlv_local_data can fail to allocate the memory for the
new TVLV block. The caller is informed about this problem with the returned
length of 0. Not checking this value results in an invalid memory access
when either tt_data or tt_change is accessed.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Fixes: 7ea7b4a14275 ("batman-adv: make the TT CRC logic VLAN specific")
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Signed-off-by: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/batman-adv/translation-table.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -2849,7 +2849,7 @@ static bool batadv_send_my_tt_response(s
 							     &tvlv_tt_data,
 							     &tt_change,
 							     &tt_len);
-		if (!tt_len)
+		if (!tt_len || !tvlv_len)
 			goto unlock;
 
 		/* Copy the last orig_node's OGM buffer */
@@ -2867,7 +2867,7 @@ static bool batadv_send_my_tt_response(s
 							     &tvlv_tt_data,
 							     &tt_change,
 							     &tt_len);
-		if (!tt_len)
+		if (!tt_len || !tvlv_len)
 			goto out;
 
 		/* fill the rest of the tvlv with the real TT entries */