diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-30 12:48:40 -0400 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2015-10-28 16:37:58 +0100 |
| commit | 89c7ab1494f614bf8323490c79d4a562e90db61b (patch) | |
| tree | 6ae0b1b88372c7f74b8c98d2b6af50763af6c842 /ipc/msg.c | |
| parent | cb0eb8ed63067553cde327241019020f84832edb (diff) | |
| download | lwn-89c7ab1494f614bf8323490c79d4a562e90db61b.tar.gz lwn-89c7ab1494f614bf8323490c79d4a562e90db61b.zip | |
Initialize msg/shm IPC objects before doing ipc_addid()
commit b9a532277938798b53178d5a66af6e2915cb27cf upstream.
As reported by Dmitry Vyukov, we really shouldn't do ipc_addid() before
having initialized the IPC object state. Yes, we initialize the IPC
object in a locked state, but with all the lockless RCU lookup work,
that IPC object lock no longer means that the state cannot be seen.
We already did this for the IPC semaphore code (see commit e8577d1f0329:
"ipc/sem.c: fully initialize sem_array before making it visible") but we
clearly forgot about msg and shm.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'ipc/msg.c')
| -rw-r--r-- | ipc/msg.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/ipc/msg.c b/ipc/msg.c index 52770bfde2a5..32aaaab15c5c 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -202,13 +202,6 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params) return retval; } - /* ipc_addid() locks msq upon success. */ - id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); - if (id < 0) { - ipc_rcu_putref(msq, msg_rcu_free); - return id; - } - msq->q_stime = msq->q_rtime = 0; msq->q_ctime = get_seconds(); msq->q_cbytes = msq->q_qnum = 0; @@ -218,6 +211,13 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params) INIT_LIST_HEAD(&msq->q_receivers); INIT_LIST_HEAD(&msq->q_senders); + /* ipc_addid() locks msq upon success. */ + id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); + if (id < 0) { + ipc_rcu_putref(msq, msg_rcu_free); + return id; + } + ipc_unlock_object(&msq->q_perm); rcu_read_unlock(); |