+ sysvipc-fix-the-ipc-structures-initialization.patch added to -mm tree

[akpm@xxxxxxxxxxxxxxxxxxxx]

The patch titled
     sysvipc: fix the ipc structures initialization
has been added to the -mm tree.  Its filename is
     sysvipc-fix-the-ipc-structures-initialization.patch

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------------------------------------------------------
Subject: sysvipc: fix the ipc structures initialization


A problem was found while reviewing the code after Bugzilla bug
http://bugzilla.kernel.org/show_bug.cgi?id=11796.

In ipc_addid(), the newly allocated ipc structure is inserted into the
ipcs tree (i.e made visible to readers) without locking it.  This is not
correct since its initialization continues after it has been inserted in
the tree.

This patch moves the ipc structure lock initialization + locking before
the actual insertion.

Signed-off-by: Nadia Derbey <Nadia.Derbey@xxxxxxxx>
Reported-by: Clement Calmels <cboulte@xxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>		[2.6.27.x]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 ipc/util.c |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff -puN ipc/util.c~sysvipc-fix-the-ipc-structures-initialization ipc/util.c
--- a/ipc/util.c~sysvipc-fix-the-ipc-structures-initialization
+++ a/ipc/util.c
@@ -266,9 +266,17 @@ int ipc_addid(struct ipc_ids* ids, struc
 	if (ids->in_use >= size)
 		return -ENOSPC;
 
+	spin_lock_init(&new->lock);
+	new->deleted = 0;
+	rcu_read_lock();
+	spin_lock(&new->lock);
+
 	err = idr_get_new(&ids->ipcs_idr, new, &id);
-	if (err)
+	if (err) {
+		spin_unlock(&new->lock);
+		rcu_read_unlock();
 		return err;
+	}
 
 	ids->in_use++;
 
@@ -280,10 +288,6 @@ int ipc_addid(struct ipc_ids* ids, struc
 		ids->seq = 0;
 
 	new->id = ipc_buildid(id, new->seq);
-	spin_lock_init(&new->lock);
-	new->deleted = 0;
-	rcu_read_lock();
-	spin_lock(&new->lock);
 	return id;
 }
 
_

Patches currently in -mm which might be from Nadia.Derbey@xxxxxxxx are

sysvipc-fix-the-ipc-structures-initialization.patch
ipc-clean-up-ipc-shmc.patch

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