Re: [PATCH] Fix Uninitialized scalar variable (UNINIT) (src/backend/access/heap/heapam_handler.c)

Em ter., 25 de ago. de 2020 às 19:54, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>
escreveu:

> Em ter., 25 de ago. de 2020 às 19:45, Alvaro Herrera <
> alvherre(at)2ndquadrant(dot)com> escreveu:
>
>> On 2020-Aug-25, Ranier Vilela wrote:
>>
>> > If the variable hscan->rs_cblock is InvalidBlockNumber the test can
>> > protect root_offsets fail.
>>
>> When does that happen?
>>
> At first pass into the while loop?
> hscan->rs_cblock is InvalidBlockNumber, what happens?
>
> Other things.
1. Even heap_get_root_tuples at line 1347, be called.
Does it fill all roots_offsets?
root_offsets[offnum - 1] is secure at this point (line 1641 or is trash)?

2. hscan->rs_cbuf is constant?
if (hscan->rs_cblock != root_blkno)
{
Page page = BufferGetPage(hscan->rs_cbuf);

LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE);
heap_get_root_tuples(page, root_offsets);
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);

root_blkno = hscan->rs_cblock;
}

This can move outside while loop?
Am I wrong or hscan do not change?

regards,
Ranier Vilela