[NETFILTER]: Fix kernel panic with REDIRECT target.
When connection tracking entry (nf_conn) is about to copy itself it can
have some of its extension users (like nat) as being already freed and
thus not required to be copied.
Actually looking at this function I suspect it was copied from
nf_nat_setup_info() and thus bug was introduced.
Report and testing from David <david@unsolicited.net>.
[ Patrick McHardy states:
I now understand whats happening:
- new connection is allocated without helper
- connection is REDIRECTed to localhost
- nf_nat_setup_info adds NAT extension, but doesn't initialize it yet
- nf_conntrack_alter_reply performs a helper lookup based on the
new tuple, finds the SIP helper and allocates a helper extension,
causing reallocation because of too little space
- nf_nat_move_storage is called with the uninitialized nat extension
So your fix is entirely correct, thanks a lot :) ]
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index 70e7997..86b465b 100644
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -607,13 +607,10 @@
struct nf_conn_nat *new_nat = nf_ct_ext_find(conntrack, NF_CT_EXT_NAT);
struct nf_conn_nat *old_nat = (struct nf_conn_nat *)old;
struct nf_conn *ct = old_nat->ct;
- unsigned int srchash;
- if (!(ct->status & IPS_NAT_DONE_MASK))
+ if (!ct || !(ct->status & IPS_NAT_DONE_MASK))
return;
- srchash = hash_by_src(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
-
write_lock_bh(&nf_nat_lock);
hlist_replace_rcu(&old_nat->bysource, &new_nat->bysource);
new_nat->ct = ct;