linux-kernel - Re: [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree

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Message-ID: <fe3b9a437be4aeab3bac68f04193cb6daaa5bee4.camel@perches.com>
Date:   Tue, 16 Jun 2020 11:53:50 -0700
From:   Joe Perches <joe@...ches.com>
To:     Waiman Long <longman@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        David Rientjes <rientjes@...gle.com>
Cc:     Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        David Sterba <dsterba@...e.cz>,
        "Jason A . Donenfeld" <Jason@...c4.com>, linux-mm@...ck.org,
        keyrings@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-amlogic@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-ppp@...r.kernel.org, wireguard@...ts.zx2c4.com,
        linux-wireless@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-scsi@...r.kernel.org, target-devel@...r.kernel.org,
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        linux-fscrypt@...r.kernel.org, ecryptfs@...r.kernel.org,
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        linux-nfs@...r.kernel.org, tipc-discussion@...ts.sourceforge.net,
        linux-security-module@...r.kernel.org,
        linux-integrity@...r.kernel.org
Subject: Re: [PATCH v4 0/3] mm, treewide: Rename kzfree() to
 kfree_sensitive()

On Mon, 2020-06-15 at 21:57 -0400, Waiman Long wrote:
>  v4:
>   - Break out the memzero_explicit() change as suggested by Dan Carpenter
>     so that it can be backported to stable.
>   - Drop the "crypto: Remove unnecessary memzero_explicit()" patch for
>     now as there can be a bit more discussion on what is best. It will be
>     introduced as a separate patch later on after this one is merged.

To this larger audience and last week without reply:
https://lore.kernel.org/lkml/573b3fbd5927c643920e1364230c296b23e7584d.camel@perches.com/

Are there _any_ fastpath uses of kfree or vfree?

Many patches have been posted recently to fix mispairings
of specific types of alloc and free functions.

To eliminate these mispairings at a runtime cost of four
comparisons, should the kfree/vfree/kvfree/kfree_const
functions be consolidated into a single kfree?

Something like the below:

   void kfree(const void *addr)
   {
   	if (is_kernel_rodata((unsigned long)addr))
   		return;

   	if (is_vmalloc_addr(addr))
   		_vfree(addr);
   	else
   		_kfree(addr);
   }

   #define kvfree		kfree
   #define vfree		kfree
   #define kfree_const	kfree