Re: [Patch net v2] rds: fix two RCU related problems
From: Cong Wang Date: Mon, 10 Sep 2018 18:27:26 -0700 > When a rds sock is bound, it is inserted into the bind_hash_table > which is protected by RCU. But when releasing rds sock, after it > is removed from this hash table, it is freed immediately without > respecting RCU grace period. This could cause some use-after-free > as reported by syzbot. > > Mark the rds sock with SOCK_RCU_FREE before inserting it into the > bind_hash_table, so that it would be always freed after a RCU grace > period. > > The other problem is in rds_find_bound(), the rds sock could be > freed in between rhashtable_lookup_fast() and rds_sock_addref(), > so we need to extend RCU read lock protection in rds_find_bound() > to close this race condition. > > Reported-and-tested-by: syzbot+8967084bcac563795...@syzkaller.appspotmail.com > Reported-by: syzbot+93a5839deb3555374...@syzkaller.appspotmail.com > Cc: Sowmini Varadhan > Cc: Santosh Shilimkar > Cc: rds-de...@oss.oracle.com > Signed-off-by: Cong Wang Applied and queued up for -stable, thanks.
Re: [Patch net v2] rds: fix two RCU related problems
On 9/10/2018 6:27 PM, Cong Wang wrote: When a rds sock is bound, it is inserted into the bind_hash_table which is protected by RCU. But when releasing rds sock, after it is removed from this hash table, it is freed immediately without respecting RCU grace period. This could cause some use-after-free as reported by syzbot. Mark the rds sock with SOCK_RCU_FREE before inserting it into the bind_hash_table, so that it would be always freed after a RCU grace period. The other problem is in rds_find_bound(), the rds sock could be freed in between rhashtable_lookup_fast() and rds_sock_addref(), so we need to extend RCU read lock protection in rds_find_bound() to close this race condition. Reported-and-tested-by: syzbot+8967084bcac563795...@syzkaller.appspotmail.com Reported-by: syzbot+93a5839deb3555374...@syzkaller.appspotmail.com Cc: Sowmini Varadhan Cc: Santosh Shilimkar Cc: rds-de...@oss.oracle.com Signed-off-by: Cong Wang --- Thank you !! Acked-by: Santosh Shilimkar
[Patch net v2] rds: fix two RCU related problems
When a rds sock is bound, it is inserted into the bind_hash_table
which is protected by RCU. But when releasing rds sock, after it
is removed from this hash table, it is freed immediately without
respecting RCU grace period. This could cause some use-after-free
as reported by syzbot.
Mark the rds sock with SOCK_RCU_FREE before inserting it into the
bind_hash_table, so that it would be always freed after a RCU grace
period.
The other problem is in rds_find_bound(), the rds sock could be
freed in between rhashtable_lookup_fast() and rds_sock_addref(),
so we need to extend RCU read lock protection in rds_find_bound()
to close this race condition.
Reported-and-tested-by: syzbot+8967084bcac563795...@syzkaller.appspotmail.com
Reported-by: syzbot+93a5839deb3555374...@syzkaller.appspotmail.com
Cc: Sowmini Varadhan
Cc: Santosh Shilimkar
Cc: rds-de...@oss.oracle.com
Signed-off-by: Cong Wang
---
net/rds/bind.c | 5 -
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/rds/bind.c b/net/rds/bind.c
index 3ab55784b637..762d2c6788a3 100644
--- a/net/rds/bind.c
+++ b/net/rds/bind.c
@@ -76,11 +76,13 @@ struct rds_sock *rds_find_bound(const struct in6_addr
*addr, __be16 port,
struct rds_sock *rs;
__rds_create_bind_key(key, addr, port, scope_id);
- rs = rhashtable_lookup_fast(_hash_table, key, ht_parms);
+ rcu_read_lock();
+ rs = rhashtable_lookup(_hash_table, key, ht_parms);
if (rs && !sock_flag(rds_rs_to_sk(rs), SOCK_DEAD))
rds_sock_addref(rs);
else
rs = NULL;
+ rcu_read_unlock();
rdsdebug("returning rs %p for %pI6c:%u\n", rs, addr,
ntohs(port));
@@ -235,6 +237,7 @@ int rds_bind(struct socket *sock, struct sockaddr *uaddr,
int addr_len)
goto out;
}
+ sock_set_flag(sk, SOCK_RCU_FREE);
ret = rds_add_bound(rs, binding_addr, , scope_id);
if (ret)
goto out;
--
2.14.4
