118 lines
3.4 KiB
Diff
118 lines
3.4 KiB
Diff
From: Linus Torvalds <torvalds@linux-foundation.org>
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Date: Wed, 30 Sep 2015 12:48:40 -0400
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Subject: Initialize msg/shm IPC objects before doing ipc_addid()
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Origin: https://git.kernel.org/linus/b9a532277938798b53178d5a66af6e2915cb27cf
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As reported by Dmitry Vyukov, we really shouldn't do ipc_addid() before
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having initialized the IPC object state. Yes, we initialize the IPC
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object in a locked state, but with all the lockless RCU lookup work,
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that IPC object lock no longer means that the state cannot be seen.
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We already did this for the IPC semaphore code (see commit e8577d1f0329:
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"ipc/sem.c: fully initialize sem_array before making it visible") but we
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clearly forgot about msg and shm.
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Reported-by: Dmitry Vyukov <dvyukov@google.com>
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Cc: Manfred Spraul <manfred@colorfullife.com>
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Cc: Davidlohr Bueso <dbueso@suse.de>
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Cc: stable@vger.kernel.org
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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ipc/msg.c | 14 +++++++-------
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ipc/shm.c | 13 +++++++------
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ipc/util.c | 8 ++++----
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3 files changed, 18 insertions(+), 17 deletions(-)
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diff --git a/ipc/msg.c b/ipc/msg.c
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index 66c4f56..1471db9 100644
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--- a/ipc/msg.c
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+++ b/ipc/msg.c
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@@ -137,13 +137,6 @@ 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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- /* ipc_addid() locks msq upon success. */
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- id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
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- if (id < 0) {
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- ipc_rcu_putref(msq, msg_rcu_free);
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- return id;
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- }
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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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@@ -153,6 +146,13 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
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INIT_LIST_HEAD(&msq->q_receivers);
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INIT_LIST_HEAD(&msq->q_senders);
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+ /* ipc_addid() locks msq upon success. */
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+ id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
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+ if (id < 0) {
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+ ipc_rcu_putref(msq, msg_rcu_free);
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+ return id;
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+ }
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+
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ipc_unlock_object(&msq->q_perm);
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rcu_read_unlock();
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diff --git a/ipc/shm.c b/ipc/shm.c
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index 222131e..4178727 100644
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--- a/ipc/shm.c
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+++ b/ipc/shm.c
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@@ -551,12 +551,6 @@ 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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-
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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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@@ -565,6 +559,13 @@ 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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+
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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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list_add(&shp->shm_clist, ¤t->sysvshm.shm_clist);
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/*
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diff --git a/ipc/util.c b/ipc/util.c
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index be42300..0f401d9 100644
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--- a/ipc/util.c
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+++ b/ipc/util.c
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@@ -237,6 +237,10 @@ 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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+
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id = idr_alloc(&ids->ipcs_idr, new,
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(next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
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GFP_NOWAIT);
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@@ -249,10 +253,6 @@ 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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-
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if (next_id < 0) {
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new->seq = ids->seq++;
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if (ids->seq > IPCID_SEQ_MAX)
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--
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2.6.0
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