Bug#16268289 LOCK_REC_VALIDATE_PAGE() MAY DEREFERENCE A POINTER TO A

             FREED LOCK

ANALYIS
-------

In 5.5 code the lock_rec_block_validate() is called after releasing
the kernel mutex. There is a chance that the lock might be invalid so,
we are getting the valgrind error on invalid read on lock->index.

FIX
---

Fix would be to copy the lock->index when we are holding the kernel mutex 
and then pass it to the lock_rec_block_validate(). This implementation
is present in 5.1 code.  

[ Approved by sunny rb.no.oracle.com/rb/r/2152/ ]

storage/innobase/lock/lock0lock.c

@@ -4980,6 +4980,7 @@ lock_rec_validate_page(
 {
 	const lock_t*	lock;
 	const rec_t*	rec;
+	dict_index_t*	index;
 	ulint		nth_lock	= 0;
 	ulint		nth_bit		= 0;
 	ulint		i;
@@ -5029,6 +5030,7 @@ loop:
 
 		if (i == 1 || lock_rec_get_nth_bit(lock, i)) {
 
+			index = lock->index;
 			rec = page_find_rec_with_heap_no(block->frame, i);
 			ut_a(rec);
 			offsets = rec_get_offsets(rec, lock->index, offsets,
@@ -5045,7 +5047,7 @@ loop:
 			check WILL break the latching order and may
 			cause a deadlock of threads. */
 
-			lock_rec_queue_validate(block, rec, lock->index,
+			lock_rec_queue_validate(block, rec, index,
 						offsets);
 
 			lock_mutex_enter_kernel();