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Date: Mon, 17 Jun 2019 17:33:20 +0300
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From: "Eli Zaretskii (eliz AT gnu DOT org) [via djgpp AT delorie DOT com]" <djgpp AT delorie DOT com>
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In-reply-to: <qe76u1$1kj8$1@gioia.aioe.org> (message from Rod Pemberton on
	Mon, 17 Jun 2019 01:05:38 -0400)
Subject: Re: malloc() returns pointer to already allocated memory
References: <158e5d20-0a90-4beb-de48-da328379d8fb AT gmail DOT com> <qe76u1$1kj8$1 AT gioia DOT aioe DOT org>
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> From: Rod Pemberton <invalid AT lkntrgzxc DOT com>
> Date: Mon, 17 Jun 2019 01:05:38 -0400
> 
> Second problem is you don't call memset() prior to using memory, nor
> free() after you're done using it.  Of course, calling memset() would
> prevent your method of "clobber" detection from working.  But, not
> calling memset() means you don't know if the magic clobber value is:
> a) from you setting it within your program, or
> b) from some random garbage values in memory.

Right.  There's a startup flag that a program could optionally set to
request that allocated memory be filled with a specific fixed value,
then tests for clobbering could work.  See the documentation of
_crt0_startup_flags in the libc manual.