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From: Alan Cox <alc@FreeBSD.org>
Date: Sun, 19 Feb 2012 00:28:49 +0000 (UTC)
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Subject: svn commit: r231904 - head/sys/kern
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Author: alc
Date: Sun Feb 19 00:28:49 2012
New Revision: 231904
URL: http://svn.freebsd.org/changeset/base/231904

Log:
  Close a race due to dropping of the map lock between creating a map entry
  for a shared mapping and marking the entry for inheritance.
  
  Reviewed by:	kib
  X-MFC after:	r231526

Modified:
  head/sys/kern/sysv_shm.c

Modified: head/sys/kern/sysv_shm.c
==============================================================================
--- head/sys/kern/sysv_shm.c	Sun Feb 19 00:21:10 2012	(r231903)
+++ head/sys/kern/sysv_shm.c	Sun Feb 19 00:28:49 2012	(r231904)
@@ -413,14 +413,12 @@ kern_shmat(td, shmid, shmaddr, shmflg)
 	vm_object_reference(shmseg->object);
 	rv = vm_map_find(&p->p_vmspace->vm_map, shmseg->object,
 	    0, &attach_va, size, (flags & MAP_FIXED) ? VMFS_NO_SPACE :
-	    VMFS_ANY_SPACE, prot, prot, 0);
+	    VMFS_ANY_SPACE, prot, prot, MAP_INHERIT_SHARE);
 	if (rv != KERN_SUCCESS) {
 		vm_object_deallocate(shmseg->object);
 		error = ENOMEM;
 		goto done2;
 	}
-	vm_map_inherit(&p->p_vmspace->vm_map,
-		attach_va, attach_va + size, VM_INHERIT_SHARE);
 
 	shmmap_s->va = attach_va;
 	shmmap_s->shmid = shmid;