Re: BUG #16082: TOAST's pglz_decompress access to uninitialized data, if the database is corrupted.

On 2019-Oct-26, Tomas Vondra wrote:

> On Sat, Oct 26, 2019 at 07:46:25AM +0000, PG Bug reporting form wrote:

> > There is two case that they are valid for invalid data. In the case 1, it
> > reads an uninitialized data in the dest. In the case 2, it reads
> > uninitialized or out-of-bound data in the dest. They are invalid.

> Well, failure like this after reading corrupted data from disk is not
> really surprising and it's hardly a bug. It's kinda intended to work
> that way, really.

There's some weight to the argument that the server should just crash
but instead report an ERRCODE_DATA_CORRUPTED message, such as what
happens with (say) invalid page headers. It would probably require a
lot more branches in the detoasting code that might decrease
performance, though. A patch would help to see how bad that would be,
though offhand I would expect it to be very bad.

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services