From: Tom Lane <tgl@sss.pgh.pa.us>
To: Daniel Gustafsson <daniel@yesql.se>
cc: pm91.arapov@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18845: DEREF_OF_NULL.RET guc_malloc possibly returns NULL
In-reply-to: <1FD7ACAC-0EBD-47D8-98B6-CC8285C571FF@yesql.se>
References: <18845-582c6e10247377ec@postgresql.org>
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 <3051193.1741961099@sss.pgh.pa.us>
 <E132D362-A669-4606-AFE1-B45C9DFCC141@yesql.se>
 <3487876.1742059377@sss.pgh.pa.us>
 <1FD7ACAC-0EBD-47D8-98B6-CC8285C571FF@yesql.se>
Comments: In-reply-to Daniel Gustafsson <daniel@yesql.se>
	message dated "Sun, 16 Mar 2025 20:59:15 +0100"
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Date: Sun, 16 Mar 2025 16:49:53 -0400
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Daniel Gustafsson <daniel@yesql.se> writes:
> Those are all good points, I initially didn't think we should touch the
> PGC_POSTMASTER cases but you are correct that avoiding back copy pastes to
> happen is a Good Thing. The attached has all these fixes added.

I think your fix in check_debug_io_direct is wrong:

-	*extra = guc_malloc(ERROR, sizeof(int));
+	*extra = guc_malloc(LOG, sizeof(int));
+	if (!*extra)
+	{
+		pfree(rawstring);
+		list_free(elemlist);
+		return false;
+	}

It looks to me like rawstring and elemlist were already freed,
so "return false" ought to be sufficient.

Also, in init_custom_variable maybe it'd be worth a comment,
along the lines of

-	gen = (struct config_generic *) guc_malloc(ERROR, sz);
+	/* As above, OOM is fatal */
+	gen = (struct config_generic *) guc_malloc(FATAL, sz);

Otherwise LGTM.

			regards, tom lane