From b9a532277938798b53178d5a66af6e2915cb27cf Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 30 Sep 2015 12:48:40 -0400 Subject: 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 Cc: Manfred Spraul Cc: Davidlohr Bueso Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds --- ipc/shm.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'ipc/shm.c') diff --git a/ipc/shm.c b/ipc/shm.c index 222131e8e38f..41787276e141 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -551,12 +551,6 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) if (IS_ERR(file)) goto no_file; - id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni); - if (id < 0) { - error = id; - goto no_id; - } - shp->shm_cprid = task_tgid_vnr(current); shp->shm_lprid = 0; shp->shm_atim = shp->shm_dtim = 0; @@ -565,6 +559,13 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) shp->shm_nattch = 0; shp->shm_file = file; shp->shm_creator = current; + + id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni); + if (id < 0) { + error = id; + goto no_id; + } + list_add(&shp->shm_clist, ¤t->sysvshm.shm_clist); /* -- cgit v1.2.3