From 43612d7c04f1a4f5e60104143918fcdf018b66ee Mon Sep 17 00:00:00 2001 From: Pablo Neira Date: Tue, 25 Nov 2014 19:54:47 +0100 Subject: [PATCH] Revert "netfilter: conntrack: fix race in __nf_conntrack_confirm against get_next_corpse" This reverts commit 5195c14c8b27cc0b18220ddbf0e5ad3328a04187. If the conntrack clashes with an existing one, it is left out of the unconfirmed list, thus, crashing when dropping the packet and releasing the conntrack since golden rule is that conntracks are always placed in any of the existing lists for traceability reasons. Reported-by: Daniel Borkmann Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=88841 Signed-off-by: Pablo Neira Ayuso Signed-off-by: David S. Miller --- net/netfilter/nf_conntrack_core.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 2c699757bccf..5016a6929085 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -611,16 +611,12 @@ __nf_conntrack_confirm(struct sk_buff *skb) */ NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); pr_debug("Confirming conntrack %p\n", ct); - - /* We have to check the DYING flag after unlink to prevent - * a race against nf_ct_get_next_corpse() possibly called from - * user context, else we insert an already 'dead' hash, blocking - * further use of that particular connection -JM. - */ - nf_ct_del_from_dying_or_unconfirmed_list(ct); + /* We have to check the DYING flag inside the lock to prevent + a race against nf_ct_get_next_corpse() possibly called from + user context, else we insert an already 'dead' hash, blocking + further use of that particular connection -JM */ if (unlikely(nf_ct_is_dying(ct))) { - nf_ct_add_to_dying_list(ct); nf_conntrack_double_unlock(hash, reply_hash); local_bh_enable(); return NF_ACCEPT; @@ -640,6 +636,8 @@ __nf_conntrack_confirm(struct sk_buff *skb) zone == nf_ct_zone(nf_ct_tuplehash_to_ctrack(h))) goto out; + nf_ct_del_from_dying_or_unconfirmed_list(ct); + /* Timer relative to confirmation time, not original setting time, otherwise we'd get timer wrap in weird delay cases. */