Acquire a read lock on the map inside of vm_map_check_protection() rather

than expecting the caller to do so.  This (1) eliminates duplicated code in
kernacc() and useracc() and (2) fixes missing synchronization in munmap().

2 files changed, 7 insertions, 4 deletions

diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c
index 678da3b..3263180 100644
--- a/sys/vm/vm_glue.c
+++ b/sys/vm/vm_glue.c
@@ -128,9 +128,7 @@ kernacc(addr, len, rw)
 	prot = rw;
 	saddr = trunc_page((vm_offset_t)addr);
 	eaddr = round_page((vm_offset_t)addr + len);
-	vm_map_lock_read(kernel_map);
 	rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot);
-	vm_map_unlock_read(kernel_map);
 	return (rv == TRUE);
 }
 
@@ -163,7 +161,7 @@ useracc(addr, len, rw)
 		return (FALSE);
 	}
 	map = &curproc->p_vmspace->vm_map;
-	vm_map_lock_read(map);
+
 	/*
 	 * We save the map hint, and restore it.  Useracc appears to distort
 	 * the map hint unnecessarily.
@@ -172,7 +170,6 @@ useracc(addr, len, rw)
 	rv = vm_map_check_protection(map,
 	    trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), prot);
 	map->hint = save_hint;
-	vm_map_unlock_read(map);
 	
 	return (rv == TRUE);
 }
diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index 3e1b4ab..094372a 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -2071,31 +2071,37 @@ vm_map_check_protection(vm_map_t map, vm_offset_t start, vm_offset_t end,
 
 	GIANT_REQUIRED;
 
+	vm_map_lock_read(map);
 	if (!vm_map_lookup_entry(map, start, &tmp_entry)) {
+		vm_map_unlock_read(map);
 		return (FALSE);
 	}
 	entry = tmp_entry;
 
 	while (start < end) {
 		if (entry == &map->header) {
+			vm_map_unlock_read(map);
 			return (FALSE);
 		}
 		/*
 		 * No holes allowed!
 		 */
 		if (start < entry->start) {
+			vm_map_unlock_read(map);
 			return (FALSE);
 		}
 		/*
 		 * Check protection associated with entry.
 		 */
 		if ((entry->protection & protection) != protection) {
+			vm_map_unlock_read(map);
 			return (FALSE);
 		}
 		/* go to next entry */
 		start = entry->end;
 		entry = entry->next;
 	}
+	vm_map_unlock_read(map);
 	return (TRUE);
 }