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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>,
	Simon Wunderlich <sw@simonwunderlich.de>
Subject: [PATCH 2/3] batman-adv: Force mac header to start of data on xmit
Date: Fri,  1 Feb 2019 12:14:11 +0100	[thread overview]
Message-ID: <20190201111412.13807-3-sw@simonwunderlich.de> (raw)
In-Reply-To: <20190201111412.13807-1-sw@simonwunderlich.de>

From: Sven Eckelmann <sven@narfation.org>

The caller of ndo_start_xmit may not already have called
skb_reset_mac_header. The returned value of skb_mac_header/eth_hdr
therefore can be in the wrong position and even outside the current skbuff.
This for example happens when the user binds to the device using a
PF_PACKET-SOCK_RAW with enabled qdisc-bypass:

  int opt = 4;
  setsockopt(sock, SOL_PACKET, PACKET_QDISC_BYPASS, &opt, sizeof(opt));

Since eth_hdr is used all over the codebase, the batadv_interface_tx
function must always take care of resetting it.

Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Reported-by: syzbot+9d7405c7faa390e60b4e@syzkaller.appspotmail.com
Reported-by: syzbot+7d20bc3f1ddddc0f9079@syzkaller.appspotmail.com
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/soft-interface.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 5db5a0a4c959..b85ca809e509 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -221,6 +221,8 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
 
 	netif_trans_update(soft_iface);
 	vid = batadv_get_vid(skb, 0);
+
+	skb_reset_mac_header(skb);
 	ethhdr = eth_hdr(skb);
 
 	switch (ntohs(ethhdr->h_proto)) {
-- 
2.11.0


WARNING: multiple messages have this Message-ID (diff)
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>,
	Simon Wunderlich <sw@simonwunderlich.de>
Subject: [B.A.T.M.A.N.] [PATCH 2/3] batman-adv: Force mac header to start of data on xmit
Date: Fri,  1 Feb 2019 12:14:11 +0100	[thread overview]
Message-ID: <20190201111412.13807-3-sw@simonwunderlich.de> (raw)
In-Reply-To: <20190201111412.13807-1-sw@simonwunderlich.de>

From: Sven Eckelmann <sven@narfation.org>

The caller of ndo_start_xmit may not already have called
skb_reset_mac_header. The returned value of skb_mac_header/eth_hdr
therefore can be in the wrong position and even outside the current skbuff.
This for example happens when the user binds to the device using a
PF_PACKET-SOCK_RAW with enabled qdisc-bypass:

  int opt = 4;
  setsockopt(sock, SOL_PACKET, PACKET_QDISC_BYPASS, &opt, sizeof(opt));

Since eth_hdr is used all over the codebase, the batadv_interface_tx
function must always take care of resetting it.

Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Reported-by: syzbot+9d7405c7faa390e60b4e@syzkaller.appspotmail.com
Reported-by: syzbot+7d20bc3f1ddddc0f9079@syzkaller.appspotmail.com
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/soft-interface.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 5db5a0a4c959..b85ca809e509 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -221,6 +221,8 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
 
 	netif_trans_update(soft_iface);
 	vid = batadv_get_vid(skb, 0);
+
+	skb_reset_mac_header(skb);
 	ethhdr = eth_hdr(skb);
 
 	switch (ntohs(ethhdr->h_proto)) {
-- 
2.11.0


  parent reply	other threads:[~2019-02-01 11:22 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-01 11:14 [PATCH 0/3] pull request for net: batman-adv 2019-02-01 Simon Wunderlich
2019-02-01 11:14 ` [B.A.T.M.A.N.] " Simon Wunderlich
2019-02-01 11:14 ` [PATCH 1/3] batman-adv: Avoid WARN on net_device without parent in netns Simon Wunderlich
2019-02-01 11:14   ` [B.A.T.M.A.N.] " Simon Wunderlich
2019-02-01 11:14 ` Simon Wunderlich [this message]
2019-02-01 11:14   ` [B.A.T.M.A.N.] [PATCH 2/3] batman-adv: Force mac header to start of data on xmit Simon Wunderlich
2019-02-01 11:14 ` [PATCH 3/3] batman-adv: release station info tidstats Simon Wunderlich
2019-02-01 11:14   ` [B.A.T.M.A.N.] " Simon Wunderlich
2019-02-01 18:19 ` [PATCH 0/3] pull request for net: batman-adv 2019-02-01 David Miller
2019-02-01 18:19   ` [B.A.T.M.A.N.] " David Miller

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