Re: Memory bug in dsnowball_lexize

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Mark Dilger <hornschnorter(at)gmail(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Memory bug in dsnowball_lexize
Date: 2019-05-23 15:46:10
Message-ID: 12465.1558626370@sss.pgh.pa.us
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Mark Dilger <hornschnorter(at)gmail(dot)com> writes:
> In src/backend/snowball/libstemmer/utilities.c, 'create_s' uses
> malloc (not palloc) to allocate memory, and on memory exhaustion
> returns NULL rather than throwing an exception.

Actually not, see macros in src/include/snowball/header.h.

> In src/backend/snowball/dict_snowball.c, 'dsnowball_lexize'
> calls 'SN_set_current' and ignores the return value, thereby
> failing to notice the error, if any.

Hm. This seems like possibly a bug, in that even if we cover the
malloc issue, there's no API guarantee that OOM is the only possible
reason for reporting failure.

> There is a comment higher up in dict_snowball.c that seems to
> use some handwaving about all this, or perhaps it is documenting
> something else entirely. In any event, I find the documentation
> about dictCtx insufficient to explain why this memory handling
> is correct.

Fair complaint --- do you want to propose some new wording that
references what header.h does?

regards, tom lane

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