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> [lizf: Backported to 3.4: adjust context] Signed-off-by: Zefan Li <lizefan@huawei.com>
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parent
f074c267d4
commit
3cda8eb001
18
ipc/msg.c
18
ipc/msg.c
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@ -198,6 +198,15 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
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return retval;
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}
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msq->q_stime = msq->q_rtime = 0;
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msq->q_ctime = get_seconds();
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msq->q_cbytes = msq->q_qnum = 0;
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msq->q_qbytes = ns->msg_ctlmnb;
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msq->q_lspid = msq->q_lrpid = 0;
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INIT_LIST_HEAD(&msq->q_messages);
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INIT_LIST_HEAD(&msq->q_receivers);
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INIT_LIST_HEAD(&msq->q_senders);
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/*
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* ipc_addid() locks msq
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*/
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@ -208,15 +217,6 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
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return id;
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}
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msq->q_stime = msq->q_rtime = 0;
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msq->q_ctime = get_seconds();
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msq->q_cbytes = msq->q_qnum = 0;
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msq->q_qbytes = ns->msg_ctlmnb;
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msq->q_lspid = msq->q_lrpid = 0;
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INIT_LIST_HEAD(&msq->q_messages);
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INIT_LIST_HEAD(&msq->q_receivers);
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INIT_LIST_HEAD(&msq->q_senders);
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msg_unlock(msq);
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return msq->q_perm.id;
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13
ipc/shm.c
13
ipc/shm.c
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@ -500,12 +500,6 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
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if (IS_ERR(file))
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goto no_file;
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id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
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if (id < 0) {
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error = id;
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goto no_id;
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}
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shp->shm_cprid = task_tgid_vnr(current);
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shp->shm_lprid = 0;
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shp->shm_atim = shp->shm_dtim = 0;
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@ -514,6 +508,13 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
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shp->shm_nattch = 0;
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shp->shm_file = file;
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shp->shm_creator = current;
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id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
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if (id < 0) {
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error = id;
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goto no_id;
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}
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/*
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* shmid gets reported as "inode#" in /proc/pid/maps.
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* proc-ps tools use this. Changing this will break them.
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@ -264,6 +264,10 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
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rcu_read_lock();
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spin_lock(&new->lock);
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current_euid_egid(&euid, &egid);
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new->cuid = new->uid = euid;
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new->gid = new->cgid = egid;
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err = idr_get_new(&ids->ipcs_idr, new, &id);
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if (err) {
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spin_unlock(&new->lock);
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@ -273,10 +277,6 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
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ids->in_use++;
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current_euid_egid(&euid, &egid);
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new->cuid = new->uid = euid;
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new->gid = new->cgid = egid;
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new->seq = ids->seq++;
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if(ids->seq > ids->seq_max)
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ids->seq = 0;
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