Re: BUG #17788: Incorrect memory access when parsing empty string as sql_standard interval

PG Bug reporting form <noreply@postgresql.org> writes:
> When executing under valgrind:
> SET IntervalStyle TO sql_standard;
> SELECT ''::interval;

> The following error is detected:
> ==00:00:00:03.574 1155861== Use of uninitialised value of size 8
> ==00:00:00:03.574 1155861==    at 0x606ADE: DecodeInterval
> (datetime.c:3368)

Good catch!  For me, it dumps core about half the time even without
using valgrind.

> This defect was introduced by the commit e39f9904.
> Before that commit the check
>     if (IntervalStyle == INTSTYLE_SQL_STANDARD && *field[0] == '-')
> was guarded by
>     if (fmask == 0)
>         return DTERR_BAD_FORMAT;
> but now field[0] is accessed unconditionally (even when nf == 0) for the
> SQL_STANDARD style.

Right.  Not checking nf > 0 wasn't great style there in any case,
but it accidentally failed to fail before.

Fix pushed --- thanks for the report!

            regards, tom lane