From: Simon Wunderlich <sw@simonwunderlich.de>
To: davem@davemloft.net
Cc: netdev@vger.kernel.org, b.a.t.m.a.n@lists.open-mesh.org,
Sven Eckelmann <sven@narfation.org>,
syzbot+355cab184197dbbfa384@syzkaller.appspotmail.com,
Antonio Quartulli <a@unstable.cc>,
Simon Wunderlich <sw@simonwunderlich.de>
Subject: [PATCH 1/2] batman-adv: Only read OGM tvlv_len after buffer len check
Date: Fri, 30 Aug 2019 09:25:01 +0200 [thread overview]
Message-ID: <20190830072502.16929-2-sw@simonwunderlich.de> (raw)
In-Reply-To: <20190830072502.16929-1-sw@simonwunderlich.de>
From: Sven Eckelmann <sven@narfation.org>
Multiple batadv_ogm_packet can be stored in an skbuff. The functions
batadv_iv_ogm_send_to_if()/batadv_iv_ogm_receive() use
batadv_iv_ogm_aggr_packet() to check if there is another additional
batadv_ogm_packet in the skb or not before they continue processing the
packet.
The length for such an OGM is BATADV_OGM_HLEN +
batadv_ogm_packet->tvlv_len. The check must first check that at least
BATADV_OGM_HLEN bytes are available before it accesses tvlv_len (which is
part of the header. Otherwise it might try read outside of the currently
available skbuff to get the content of tvlv_len.
Fixes: ef26157747d4 ("batman-adv: tvlv - basic infrastructure")
Reported-by: syzbot+355cab184197dbbfa384@syzkaller.appspotmail.com
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Acked-by: Antonio Quartulli <a@unstable.cc>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
net/batman-adv/bat_iv_ogm.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c
index 240ed70912d6..d78938e3e008 100644
--- a/net/batman-adv/bat_iv_ogm.c
+++ b/net/batman-adv/bat_iv_ogm.c
@@ -277,17 +277,23 @@ static u8 batadv_hop_penalty(u8 tq, const struct batadv_priv *bat_priv)
* batadv_iv_ogm_aggr_packet() - checks if there is another OGM attached
* @buff_pos: current position in the skb
* @packet_len: total length of the skb
- * @tvlv_len: tvlv length of the previously considered OGM
+ * @ogm_packet: potential OGM in buffer
*
* Return: true if there is enough space for another OGM, false otherwise.
*/
-static bool batadv_iv_ogm_aggr_packet(int buff_pos, int packet_len,
- __be16 tvlv_len)
+static bool
+batadv_iv_ogm_aggr_packet(int buff_pos, int packet_len,
+ const struct batadv_ogm_packet *ogm_packet)
{
int next_buff_pos = 0;
- next_buff_pos += buff_pos + BATADV_OGM_HLEN;
- next_buff_pos += ntohs(tvlv_len);
+ /* check if there is enough space for the header */
+ next_buff_pos += buff_pos + sizeof(*ogm_packet);
+ if (next_buff_pos > packet_len)
+ return false;
+
+ /* check if there is enough space for the optional TVLV */
+ next_buff_pos += ntohs(ogm_packet->tvlv_len);
return (next_buff_pos <= packet_len) &&
(next_buff_pos <= BATADV_MAX_AGGREGATION_BYTES);
@@ -315,7 +321,7 @@ static void batadv_iv_ogm_send_to_if(struct batadv_forw_packet *forw_packet,
/* adjust all flags and log packets */
while (batadv_iv_ogm_aggr_packet(buff_pos, forw_packet->packet_len,
- batadv_ogm_packet->tvlv_len)) {
+ batadv_ogm_packet)) {
/* we might have aggregated direct link packets with an
* ordinary base packet
*/
@@ -1704,7 +1710,7 @@ static int batadv_iv_ogm_receive(struct sk_buff *skb,
/* unpack the aggregated packets and process them one by one */
while (batadv_iv_ogm_aggr_packet(ogm_offset, skb_headlen(skb),
- ogm_packet->tvlv_len)) {
+ ogm_packet)) {
batadv_iv_ogm_process(skb, ogm_offset, if_incoming);
ogm_offset += BATADV_OGM_HLEN;
--
2.20.1
next prev parent reply other threads:[~2019-08-30 7:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-30 7:25 [PATCH 0/2] pull request for net: batman-adv 2019-08-30 Simon Wunderlich
2019-08-30 7:25 ` Simon Wunderlich [this message]
2019-08-30 7:25 ` [PATCH 2/2] batman-adv: Only read OGM2 tvlv_len after buffer len check Simon Wunderlich
2019-08-31 20:18 ` [PATCH 0/2] pull request for net: batman-adv 2019-08-30 David Miller
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