From f3fe6cb4c18df64d43027bdea0e3aaeb1af78c28 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 590fc566cab88e9de6f37ba21aa8047608f46942. 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 2c699757bccf2..5016a6929085e 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. */ -- 2.39.5