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Groups > linux.kernel > #1650751

[PATCH 16/20] ipc: Move atomic_set() to where it is needed

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From: Kees Cook <keescook@chromium.org>

Only after ipc_addid() has succeeded will refcounting be used, so
move initialization into ipc_addid() and remove from open-coded
*_alloc() routines.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
---
 ipc/msg.c  | 2 --
 ipc/sem.c  | 1 -
 ipc/shm.c  | 2 --
 ipc/util.c | 1 +
 4 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/ipc/msg.c b/ipc/msg.c
index cd90bfd..770342e 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -117,8 +117,6 @@ static struct msg_queue *msg_alloc(void)
 	if (unlikely(!msq))
 		return NULL;
 
-	atomic_set(&msq->q_perm.refcount, 1);
-
 	return msq;
 }
 
diff --git a/ipc/sem.c b/ipc/sem.c
index 2b2ed56..5f13773 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -465,7 +465,6 @@ static struct sem_array *sem_alloc(size_t nsems)
 		return NULL;
 
 	memset(sma, 0, size);
-	atomic_set(&sma->sem_perm.refcount, 1);
 
 	return sma;
 }
diff --git a/ipc/shm.c b/ipc/shm.c
index cb1d97e..b85db5a 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -526,8 +526,6 @@ static struct shmid_kernel *shm_alloc(void)
 	if (unlikely(!shp))
 		return NULL;
 
-	atomic_set(&shp->shm_perm.refcount, 1);
-
 	return shp;
 }
 
diff --git a/ipc/util.c b/ipc/util.c
index 2428dd4..1a2cb02 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -232,6 +232,7 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
 
 	idr_preload(GFP_KERNEL);
 
+	atomic_set(&new->refcount, 1);
 	spin_lock_init(&new->lock);
 	new->deleted = false;
 	rcu_read_lock();
-- 
2.9.3

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[PATCH 0/20 V3] Misc cleanups for ipc Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 05/20] ipc/sem: Do not use ipc_rcu_free() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 08/20] ipc/util: Drop ipc_rcu_free() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 15/20] ipc/msg.c: Avoid ipc_rcu_putref for failed ipc_addid() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 19/20] ipc/sem: Drop __sem_free() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 20/20] ipc/util.h: Update documentation for ipc_getref() and ipc_putref() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 09/20] ipc/sem: Avoid ipc_rcu_alloc() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 17/20] ipc/shm: Remove special shm_alloc/free Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 11/20] ipc/msg: Avoid ipc_rcu_alloc() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 12/20] ipc/util: Drop ipc_rcu_alloc() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 16/20] ipc: Move atomic_set() to where it is needed Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 04/20] ipc: Drop non-RCU allocation Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
    Re: [PATCH 04/20] ipc: Drop non-RCU allocation Kees Cook <keescook@chromium.org> - 2017-05-25 21:40 +0200
  [PATCH 03/20] include/linux/sem.h: Correctly document sem_ctime Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 07/20] ipc/msg: Do not use ipc_rcu_free() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  [PATCH 10/20] ipc/shm: Avoid ipc_rcu_alloc() Manfred Spraul <manfred@colorfullife.com> - 2017-05-25 21:00 +0200
  Re: [PATCH 0/20 V3] Misc cleanups for ipc Kees Cook <keescook@chromium.org> - 2017-05-25 21:50 +0200
    Re: [PATCH 0/20 V3] Misc cleanups for ipc Manfred Spraul <manfred@colorfullife.com> - 2017-05-26 04:00 +0200

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