This is a note to let you know that I've just added the patch titled

race of lockd inetaddr notifiers vs nlmsvc_rqst change

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: race-of-lockd-inetaddr-notifiers-vs-nlmsvc_rqst-change.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Thu Feb 1 13:45:42 CET 2018

From: Vasily Averin vvs@virtuozzo.com Date: Fri, 10 Nov 2017 10:19:26 +0300 Subject: race of lockd inetaddr notifiers vs nlmsvc_rqst change

From: Vasily Averin vvs@virtuozzo.com

[ Upstream commit 6b18dd1c03e07262ea0866084856b2a3c5ba8d09 ]

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 are no longer in use.

Note that nlmsvc_rqst can be temporally set to ERR_PTR, so the "if (nlmsvc_rqst)" check in notifiers is insufficient on its own.

Signed-off-by: Vasily Averin vvs@virtuozzo.com Tested-by: Scott Mayhew smayhew@redhat.com Signed-off-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/lockd/svc.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)

--- 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); + unsigned int lockd_net_id;

/* @@ -292,7 +295,8 @@ static int lockd_inetaddr_event(struct n 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) { @@ -303,6 +307,8 @@ static int lockd_inetaddr_event(struct n 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; @@ -319,7 +325,8 @@ static int lockd_inet6addr_event(struct 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) { @@ -331,6 +338,8 @@ static int lockd_inet6addr_event(struct 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; @@ -347,10 +356,12 @@ static void lockd_unregister_notifiers(v #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); } @@ -375,6 +386,7 @@ static int lockd_start_svc(struct svc_se goto out_rqst; }

+ atomic_inc(&nlm_ntf_refcnt); svc_sock_update_bufs(serv); serv->sv_maxconn = nlm_max_connections;

Patches currently in stable-queue which might be from vvs@virtuozzo.com are

queue-4.14/lockd-fix-list_add-double-add-caused-by-legacy-signal-interface.patch queue-4.14/grace-replace-bug_on-by-warn_once-in-exit_net-hook.patch queue-4.14/perf-core-fix-memory-leak-triggered-by-perf-namespace.patch queue-4.14/race-of-lockd-inetaddr-notifiers-vs-nlmsvc_rqst-change.patch