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authorLinus Torvalds <torvalds@linux-foundation.org>2015-09-30 12:48:40 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-22 14:37:51 -0700
commit162d3c2fd8b7ca5971fc1a366013463d7511afdd (patch)
treef21d44c8902b552420344ed8c2ad64769a1d3890
parent760f9dc129d41a76934d149ccc762590006a6f6a (diff)
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--ipc/msg.c14
-rw-r--r--ipc/shm.c12
-rw-r--r--ipc/util.c8
3 files changed, 17 insertions, 17 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();
diff --git a/ipc/shm.c b/ipc/shm.c
index 6dc55af8a29b..08b14f69d6cf 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -544,12 +544,6 @@ 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;
@@ -559,6 +553,12 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
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;
+ }
+
/*
* shmid gets reported as "inode#" in /proc/pid/maps.
* proc-ps tools use this. Changing this will break them.
diff --git a/ipc/util.c b/ipc/util.c
index 7684f41bce76..735342570a87 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -292,6 +292,10 @@ 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);
@@ -304,10 +308,6 @@ 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 > ids->seq_max)