From b5495ddce4659122180b5fee6fc52dc5196e0918 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() [ Upstream commit b9a532277938798b53178d5a66af6e2915cb27cf ] 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 Signed-off-by: Sasha Levin --- ipc/msg.c | 14 +++++++------- ipc/shm.c | 13 +++++++------ ipc/util.c | 8 ++++---- 3 files changed, 18 insertions(+), 17 deletions(-) (limited to 'ipc') diff --git a/ipc/msg.c b/ipc/msg.c index c5d8e3749985..cfc8b388332d 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(); diff --git a/ipc/shm.c b/ipc/shm.c index 01454796ba3c..2511771a9a07 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -549,12 +549,6 @@ 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; @@ -563,6 +557,13 @@ 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); /* diff --git a/ipc/util.c b/ipc/util.c index 88adc329888c..bc72cbf929da 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -277,6 +277,10 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size) rcu_read_lock(); spin_lock(&new->lock); + current_euid_egid(&euid, &egid); + new->cuid = new->uid = euid; + new->gid = new->cgid = egid; + id = idr_alloc(&ids->ipcs_idr, new, (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0, GFP_NOWAIT); @@ -289,10 +293,6 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size) ids->in_use++; - current_euid_egid(&euid, &egid); - new->cuid = new->uid = euid; - new->gid = new->cgid = egid; - if (next_id < 0) { new->seq = ids->seq++; if (ids->seq > IPCID_SEQ_MAX) -- cgit v1.2.1