netfilter: log: netns NULL ptr bug when calling from conntrack

Since (69b34fb netfilter: xt_LOG: add net namespace support
for xt_LOG), we hit this:

[ 4224.708977] BUG: unable to handle kernel NULL pointer dereference at 0000000000000388
[ 4224.709074] IP: [<ffffffff8147f699>] ipt_log_packet+0x29/0x270

when callling log functions from conntrack both in and out
are NULL i.e. the net pointer is invalid.

Adding struct net *net in call to nf_logfn() will secure that
there always is a vaild net ptr.

Reported as netfilter's bugzilla bug 818:
https://bugzilla.netfilter.org/show_bug.cgi?id=818

Reported-by: Ronald <ronald645@gmail.com>
Signed-off-by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 16 insertions, 13 deletions

diff --git a/net/bridge/netfilter/ebt_log.c b/net/bridge/netfilter/ebt_log.c
index 9878eb8204c..19c37a4929b 100644
--- a/net/bridge/netfilter/ebt_log.c
+++ b/net/bridge/netfilter/ebt_log.c
@@ -72,13 +72,12 @@ print_ports(const struct sk_buff *skb, uint8_t protocol, int offset)
 }
 
 static void
-ebt_log_packet(u_int8_t pf, unsigned int hooknum,
-   const struct sk_buff *skb, const struct net_device *in,
-   const struct net_device *out, const struct nf_loginfo *loginfo,
-   const char *prefix)
+ebt_log_packet(struct net *net, u_int8_t pf, unsigned int hooknum,
+	       const struct sk_buff *skb, const struct net_device *in,
+	       const struct net_device *out, const struct nf_loginfo *loginfo,
+	       const char *prefix)
 {
 	unsigned int bitmask;
-	struct net *net = dev_net(in ? in : out);
 
 	/* FIXME: Disabled from containers until syslog ns is supported */
 	if (!net_eq(net, &init_net))
@@ -191,7 +190,7 @@ ebt_log_tg(struct sk_buff *skb, const struct xt_action_param *par)
 		nf_log_packet(net, NFPROTO_BRIDGE, par->hooknum, skb,
 			      par->in, par->out, &li, "%s", info->prefix);
 	else
-		ebt_log_packet(NFPROTO_BRIDGE, par->hooknum, skb, par->in,
+		ebt_log_packet(net, NFPROTO_BRIDGE, par->hooknum, skb, par->in,
 			       par->out, &li, info->prefix);
 	return EBT_CONTINUE;
 }
diff --git a/net/bridge/netfilter/ebt_ulog.c b/net/bridge/netfilter/ebt_ulog.c
index fc1905c5141..df0364aa12d 100644
--- a/net/bridge/netfilter/ebt_ulog.c
+++ b/net/bridge/netfilter/ebt_ulog.c
@@ -131,14 +131,16 @@ static struct sk_buff *ulog_alloc_skb(unsigned int size)
 	return skb;
 }
 
-static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
-   const struct net_device *in, const struct net_device *out,
-   const struct ebt_ulog_info *uloginfo, const char *prefix)
+static void ebt_ulog_packet(struct net *net, unsigned int hooknr,
+			    const struct sk_buff *skb,
+			    const struct net_device *in,
+			    const struct net_device *out,
+			    const struct ebt_ulog_info *uloginfo,
+			    const char *prefix)
 {
 	ebt_ulog_packet_msg_t *pm;
 	size_t size, copy_len;
 	struct nlmsghdr *nlh;
-	struct net *net = dev_net(in ? in : out);
 	struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
 	unsigned int group = uloginfo->nlgroup;
 	ebt_ulog_buff_t *ub = &ebt->ulog_buffers[group];
@@ -233,7 +235,7 @@ unlock:
 }
 
 /* this function is registered with the netfilter core */
-static void ebt_log_packet(u_int8_t pf, unsigned int hooknum,
+static void ebt_log_packet(struct net *net, u_int8_t pf, unsigned int hooknum,
    const struct sk_buff *skb, const struct net_device *in,
    const struct net_device *out, const struct nf_loginfo *li,
    const char *prefix)
@@ -252,13 +254,15 @@ static void ebt_log_packet(u_int8_t pf, unsigned int hooknum,
 		strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
 	}
 
-	ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
+	ebt_ulog_packet(net, hooknum, skb, in, out, &loginfo, prefix);
 }
 
 static unsigned int
 ebt_ulog_tg(struct sk_buff *skb, const struct xt_action_param *par)
 {
-	ebt_ulog_packet(par->hooknum, skb, par->in, par->out,
+	struct net *net = dev_net(par->in ? par->in : par->out);
+
+	ebt_ulog_packet(net, par->hooknum, skb, par->in, par->out,
 	                par->targinfo, NULL);
 	return EBT_CONTINUE;
 }