[PATCH] SYSVIPC - Fix the ipc structures initialization

[Nadia . Derbey]

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.

Regards,
Nadia


Signed-off-by: Nadia Derbey <Nadia.Derbey@xxxxxxxx>

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

Index: linux-2.6.27/ipc/util.c
===================================================================
--- linux-2.6.27.orig/ipc/util.c	2008-10-23 15:20:46.000000000 +0200
+++ linux-2.6.27/ipc/util.c	2008-10-28 16:52:17.000000000 +0100
@@ -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;
 }
 

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