Re: Bug: Reading from single byte character column type may cause out of bounds memory reads.

Aleksander Alekseev <aleksander(at)timescale(dot)com> writes:
> Although the bug is easy to fix for this particular case (see the
> patch) I'm not sure if this solution is general enough. E.g. is there
> something that generally prevents pg_mblen() from doing out of bound
> reading in cases similar to this one? Should we prevent such an INSERT
> from happening instead?

This is ultimately down to char_text() generating a string that's alleged
to be a valid "text" type value, but it contains illegally-encoded data.
Where we need to fix it is there: if we try to make every single
text-using function be 100% bulletproof against wrongly-encoded data,
we'll still be fixing bugs at the heat death of the universe.

I complained about this in [1], but that thread died off before reaching a
clear consensus about exactly what to do.

regards, tom lane

[1] https://www.postgresql.org/message-id/flat/2318797.1638558730%40sss.pgh.pa.us