Greetings, * Ants Aasma (a...@cybertec.at) wrote: > On Wed, 13 Oct 2021 at 02:20, Bruce Momjian <br...@momjian.us> wrote: > > On Wed, Oct 13, 2021 at 12:48:51AM +0300, Ants Aasma wrote: > > > On Wed, 13 Oct 2021 at 00:25, Bruce Momjian <br...@momjian.us> wrote: > > > > > > On Tue, Oct 12, 2021 at 11:21:28PM +0300, Ants Aasma wrote: > > > > Page encrypting to all zeros is for all practical purposes > > impossible to > > > hit. > > > > Basically an attacker would have to be able to arbitrarily set the > > whole > > > > contents of the page and they would then achieve that this page > > gets > > > ignored. > > > > > > Uh, how do we know that valid data can't produce an encrypted > > all-zero > > > page? > > > > > > > > > Because the chances of that happening by accident are equivalent to > > making a > > > series of commits to postgres and ending up with the same git commit > > hash 400 > > > times in a row. > > > > Yes, 256^8192 is 1e+19728, but why not just assume a page LSN=0 is an > > empty page, and if not, an error? Seems easier than checking if each > > page contains all zeros every time. > > > > We already check it anyway, see PageIsVerifiedExtended().
Right- we check the LSN along with the rest of the page there. Thanks, Stephen
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