[Devel] [PATCH RHEL7 COMMIT] lockd: race of lockd inetaddr notifiers with nlmsvc_rqst change
Konstantin Khorenko
khorenko at virtuozzo.com
Tue Oct 31 13:16:19 MSK 2017
The commit is pushed to "branch-rh7-3.10.0-693.1.1.vz7.37.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.1.1.vz7.37.20
------>
commit ff9269036e800b15c3d7feb81b4fefce461527f6
Author: Vasily Averin <vvs at virtuozzo.com>
Date: Tue Oct 31 13:16:19 2017 +0300
lockd: race of lockd inetaddr notifiers with nlmsvc_rqst change
lockd_inet[6]addr_event use nlmsvc_rqst without taken nlmsvc_mutex,
nlmsvc_rqst can be changed during execution of notifiers and crash the host.
Patch enables access to nlmsvc_rqst only when it was correctly initialized
and delays its cleanup until notifiers exit.
https://jira.sw.ru/browse/PSBM-76103
Signed-off-by: Vasily Averin <vvs at virtuozzo.com>
---
fs/lockd/svc.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index ba276bf..5920bae 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -57,6 +57,9 @@ static struct task_struct *nlmsvc_task;
static struct svc_rqst *nlmsvc_rqst;
unsigned long nlmsvc_timeout;
+atomic_t nlm_ntf_refcnt = ATOMIC_INIT(0);
+DECLARE_WAIT_QUEUE_HEAD(nlm_ntf_wq);
+
int lockd_net_id;
/*
@@ -289,7 +292,8 @@ static int lockd_inetaddr_event(struct notifier_block *this,
struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
struct sockaddr_in sin;
- if (event != NETDEV_DOWN)
+ if ((event != NETDEV_DOWN) ||
+ !atomic_inc_not_zero(&nlm_ntf_refcnt))
goto out;
if (nlmsvc_rqst) {
@@ -300,6 +304,8 @@ static int lockd_inetaddr_event(struct notifier_block *this,
svc_age_temp_xprts_now(nlmsvc_rqst->rq_server,
(struct sockaddr *)&sin);
}
+ atomic_dec(&nlm_ntf_refcnt);
+ wake_up(&nlm_ntf_wq);
out:
return NOTIFY_DONE;
@@ -316,7 +322,8 @@ static int lockd_inet6addr_event(struct notifier_block *this,
struct inet6_ifaddr *ifa = (struct inet6_ifaddr *)ptr;
struct sockaddr_in6 sin6;
- if (event != NETDEV_DOWN)
+ if ((event != NETDEV_DOWN) ||
+ !atomic_inc_not_zero(&nlm_ntf_refcnt))
goto out;
if (nlmsvc_rqst) {
@@ -326,6 +333,8 @@ static int lockd_inet6addr_event(struct notifier_block *this,
svc_age_temp_xprts_now(nlmsvc_rqst->rq_server,
(struct sockaddr *)&sin6);
}
+ atomic_dec(&nlm_ntf_refcnt);
+ wake_up(&nlm_ntf_wq);
out:
return NOTIFY_DONE;
@@ -342,10 +351,12 @@ static void lockd_unregister_notifiers(void)
#if IS_ENABLED(CONFIG_IPV6)
unregister_inet6addr_notifier(&lockd_inet6addr_notifier);
#endif
+ wait_event(nlm_ntf_wq, atomic_read(&nlm_ntf_refcnt) == 0);
}
static void lockd_svc_exit_thread(void)
{
+ atomic_dec(&nlm_ntf_refcnt);
lockd_unregister_notifiers();
svc_exit_thread(nlmsvc_rqst);
}
@@ -369,6 +380,7 @@ static int lockd_start_svc(struct svc_serv *serv)
goto out_rqst;
}
+ atomic_inc(&nlm_ntf_refcnt);
svc_sock_update_bufs(serv);
serv->sv_maxconn = nlm_max_connections;
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