From 7c36bff505b117a9fd43bc644e3427ae1173e10a Mon Sep 17 00:00:00 2001 From: Mohamad Ayyash Date: Tue, 13 Jan 2015 19:20:44 -0800 Subject: [PATCH] xt_qtaguid: Use sk_callback_lock read locks before reading sk->sk_socket It prevents a kernel panic when accessing sk->sk_socket fields due to NULLing sk->sk_socket when sock_orphan is called through sk_common_release. Change-Id: I4aa46b4e2d8600e4d4ef8dcdd363aa4e6e5f8433 Signed-off-by: Mohamad Ayyash (cherry picked from commit cdea0ebcb8bcfe57688f6cb692b49e550ebd9796) Signed-off-by: John Stultz --- net/netfilter/xt_qtaguid.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/netfilter/xt_qtaguid.c b/net/netfilter/xt_qtaguid.c index 9664bec1091c..e33be3aaf094 100644 --- a/net/netfilter/xt_qtaguid.c +++ b/net/netfilter/xt_qtaguid.c @@ -1658,6 +1658,7 @@ static bool qtaguid_mt(const struct sk_buff *skb, struct xt_action_param *par) struct sock *sk; kuid_t sock_uid; bool res; + bool set_sk_callback_lock = false; if (unlikely(module_passive)) return (info->match ^ info->invert) == 0; @@ -1715,6 +1716,8 @@ static bool qtaguid_mt(const struct sk_buff *skb, struct xt_action_param *par) MT_DEBUG("qtaguid[%d]: sk=%p got_sock=%d fam=%d proto=%d\n", par->hooknum, sk, got_sock, par->family, ipx_proto(skb, par)); if (sk != NULL) { + set_sk_callback_lock = true; + read_lock_bh(&sk->sk_callback_lock); MT_DEBUG("qtaguid[%d]: sk=%p->sk_socket=%p->file=%p\n", par->hooknum, sk, sk->sk_socket, sk->sk_socket ? sk->sk_socket->file : (void *)-1LL); @@ -1801,6 +1804,8 @@ static bool qtaguid_mt(const struct sk_buff *skb, struct xt_action_param *par) put_sock_ret_res: if (got_sock) xt_socket_put_sk(sk); + if (set_sk_callback_lock) + read_unlock_bh(&sk->sk_callback_lock); ret_res: MT_DEBUG("qtaguid[%d]: left %d\n", par->hooknum, res); return res; -- 2.20.1