lkml.org 
[lkml]   [2007]   [Dec]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch 37/60] netfilter: Fix kernel panic with REDIRECT target.
2.6.23-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>

This patch fixes a NAT regression in 2.6.23, resulting in a
crash when a connection is NATed and matches a conntrack
helper after NAT.

Please apply, thanks.
[NETFILTER]: Fix kernel panic with REDIRECT target.

Upstream commit 1f305323ff5b9ddc1a4346d36072bcdb58f3f68a

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/ipv4/netfilter/nf_nat_core.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -607,13 +607,10 @@ static void nf_nat_move_storage(struct n
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;
--


\
 
 \ /
  Last update: 2007-12-13 08:15    [W:0.290 / U:13.744 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site