diff options
| author | bill bonaparte <programme110@gmail.com> | 2014-11-06 14:36:48 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-12-06 15:57:34 -0800 |
| commit | 88fd8709858b9cd94e2d28b4b3cac4b752f0683a (patch) | |
| tree | 78559d8e2c21ae2b97605309aeb7776020cf93d1 /net | |
| parent | 2b385019adf661fa20ae263103096acc4e05447d (diff) | |
netfilter: conntrack: fix race in __nf_conntrack_confirm against get_next_corpse
commit 5195c14c8b27cc0b18220ddbf0e5ad3328a04187 upstream.
After removal of the central spinlock nf_conntrack_lock, in
commit 93bb0ceb75be2 ("netfilter: conntrack: remove central
spinlock nf_conntrack_lock"), it is possible to race against
get_next_corpse().
The race is against the get_next_corpse() cleanup on
the "unconfirmed" list (a per-cpu list with seperate locking),
which set the DYING bit.
Fix this race, in __nf_conntrack_confirm(), by removing the CT
from unconfirmed list before checking the DYING bit. In case
race occured, re-add the CT to the dying list.
While at this, fix coding style of the comment that has been
updated.
Fixes: 93bb0ceb75be2 ("netfilter: conntrack: remove central spinlock nf_conntrack_lock")
Reported-by: bill bonaparte <programme110@gmail.com>
Signed-off-by: bill bonaparte <programme110@gmail.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/nf_conntrack_core.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index de88c4ab5146..ec94ba94079f 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -611,12 +611,16 @@ __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 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 */ + + /* 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); 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; @@ -636,8 +640,6 @@ __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. */ |