| Message ID | 20180208055918.20411-2-xiyou.wangcong@gmail.com |
|---|---|
| State | Changes Requested |
| Delegated to: | Pablo Neira |
| Headers | show |
| Series | [net] ipt_CLUSTERIP: fix a refcount bug in clusterip_config_find_get() | expand |
Cong Wang <xiyou.wangcong@gmail.com> wrote: > In clusterip_config_find_get() we hold RCU read lock so it could > run concurrently with clusterip_config_entry_put(), as a result, > the refcnt could go back to 1 from 0, which leads to a double > list_del()... Just replace refcount_inc() with > refcount_inc_not_zero(), as for c->refcount. > > Fixes: d73f33b16883 ("netfilter: CLUSTERIP: RCU conversion") > Cc: Eric Dumazet <eric.dumazet@gmail.com> > Cc: Pablo Neira Ayuso <pablo@netfilter.org> > Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> > --- > net/ipv4/netfilter/ipt_CLUSTERIP.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c > index 1ff72b87a066..4537b1686c7c 100644 > --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c > +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c > @@ -154,8 +154,10 @@ clusterip_config_find_get(struct net *net, __be32 clusterip, int entry) > #endif > if (unlikely(!refcount_inc_not_zero(&c->refcount))) > c = NULL; > - else if (entry) > - refcount_inc(&c->entries); > + else if (entry) { > + if (unlikely(!refcount_inc_not_zero(&c->entries))) this needs to call clusterip_config_put(c); too, else we leak one reference. Other than that this looks good. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Feb 8, 2018 at 12:01 AM, Florian Westphal <fw@strlen.de> wrote: > Cong Wang <xiyou.wangcong@gmail.com> wrote: >> In clusterip_config_find_get() we hold RCU read lock so it could >> run concurrently with clusterip_config_entry_put(), as a result, >> the refcnt could go back to 1 from 0, which leads to a double >> list_del()... Just replace refcount_inc() with >> refcount_inc_not_zero(), as for c->refcount. >> >> Fixes: d73f33b16883 ("netfilter: CLUSTERIP: RCU conversion") >> Cc: Eric Dumazet <eric.dumazet@gmail.com> >> Cc: Pablo Neira Ayuso <pablo@netfilter.org> >> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> >> --- >> net/ipv4/netfilter/ipt_CLUSTERIP.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c >> index 1ff72b87a066..4537b1686c7c 100644 >> --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c >> +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c >> @@ -154,8 +154,10 @@ clusterip_config_find_get(struct net *net, __be32 clusterip, int entry) >> #endif >> if (unlikely(!refcount_inc_not_zero(&c->refcount))) >> c = NULL; >> - else if (entry) >> - refcount_inc(&c->entries); >> + else if (entry) { >> + if (unlikely(!refcount_inc_not_zero(&c->entries))) > > this needs to call clusterip_config_put(c); too, else we leak one > reference. > > Other than that this looks good. Right, good catch! I will send v2. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c index 1ff72b87a066..4537b1686c7c 100644 --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -154,8 +154,10 @@ clusterip_config_find_get(struct net *net, __be32 clusterip, int entry) #endif if (unlikely(!refcount_inc_not_zero(&c->refcount))) c = NULL; - else if (entry) - refcount_inc(&c->entries); + else if (entry) { + if (unlikely(!refcount_inc_not_zero(&c->entries))) + c = NULL; + } } rcu_read_unlock_bh();
In clusterip_config_find_get() we hold RCU read lock so it could run concurrently with clusterip_config_entry_put(), as a result, the refcnt could go back to 1 from 0, which leads to a double list_del()... Just replace refcount_inc() with refcount_inc_not_zero(), as for c->refcount. Fixes: d73f33b16883 ("netfilter: CLUSTERIP: RCU conversion") Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)