@@ -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();
@@ -547,12 +547,6 @@ 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;
@@ -562,6 +556,12 @@ 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.
@@ -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)
This is a note to let you know that I have just added a patch titled Initialize msg/shm IPC objects before doing ipc_addid() to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt19. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From d19d5bce7087879145582e0d2940532232e3decd Mon Sep 17 00:00:00 2001 From: Linus Torvalds <torvalds@linux-foundation.org> Date: Wed, 30 Sep 2015 12:48:40 -0400 Subject: 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> [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- ipc/msg.c | 14 +++++++------- ipc/shm.c | 12 ++++++------ ipc/util.c | 8 ++++---- 3 files changed, 17 insertions(+), 17 deletions(-)