From 9d2c9488cedb666bc8206fbdcdc1575e0fbc5929 Mon Sep 17 00:00:00 2001 From: Linus Lüssing Date: Tue, 6 Aug 2013 20:21:15 +0200 Subject: batman-adv: fix potential kernel paging errors for unicast transmissions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There are several functions which might reallocate skb data. Currently some places keep reusing their old ethhdr pointer regardless of whether they became invalid after such a reallocation or not. This potentially leads to kernel paging errors. This patch fixes these by refetching the ethdr pointer after the potential reallocations. Signed-off-by: Linus Lüssing Signed-off-by: Marek Lindner Signed-off-by: Antonio Quartulli --- net/batman-adv/soft-interface.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'net/batman-adv/soft-interface.c') diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 700d0b49742..0f04e1c302b 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -180,6 +180,9 @@ static int batadv_interface_tx(struct sk_buff *skb, if (batadv_bla_tx(bat_priv, skb, vid)) goto dropped; + /* skb->data might have been reallocated by batadv_bla_tx() */ + ethhdr = (struct ethhdr *)skb->data; + /* Register the client MAC in the transtable */ if (!is_multicast_ether_addr(ethhdr->h_source)) batadv_tt_local_add(soft_iface, ethhdr->h_source, skb->skb_iif); @@ -220,6 +223,10 @@ static int batadv_interface_tx(struct sk_buff *skb, default: break; } + + /* reminder: ethhdr might have become unusable from here on + * (batadv_gw_is_dhcp_target() might have reallocated skb data) + */ } /* ethernet packet should be broadcasted */ @@ -266,7 +273,7 @@ static int batadv_interface_tx(struct sk_buff *skb, /* unicast packet */ } else { if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_OFF) { - ret = batadv_gw_out_of_range(bat_priv, skb, ethhdr); + ret = batadv_gw_out_of_range(bat_priv, skb); if (ret) goto dropped; } -- cgit v1.2.3-70-g09d2