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authorLinus Torvalds <torvalds@linux-foundation.org>2015-09-30 18:48:40 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-30 18:48:40 +0200
commitb9a532277938798b53178d5a66af6e2915cb27cf (patch)
tree61938755aa03a1fcde29b3fcea8b29ef962af58f /ipc/msg.c
parentMerge branch 'stable' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetca... (diff)
downloadlinux-b9a532277938798b53178d5a66af6e2915cb27cf.tar.xz
linux-b9a532277938798b53178d5a66af6e2915cb27cf.zip
Initialize msg/shm IPC objects before doing ipc_addid()
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> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/msg.c')
-rw-r--r--ipc/msg.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/ipc/msg.c b/ipc/msg.c
index 66c4f567eb73..1471db9a7e61 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -137,13 +137,6 @@ 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;
@@ -153,6 +146,13 @@ 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();