linux-kernel - Re: [PATCH 1/2] mm, treewide: Rename kzfree() to kfree

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Message-ID: <9d084be2-29a3-7757-9386-20dbaeb5fc24@redhat.com>
Date:   Mon, 15 Jun 2020 14:39:59 -0400
From:   Waiman Long <longman@...hat.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     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>,
        Joe Perches <joe@...ches.com>,
        Matthew Wilcox <willy@...radead.org>,
        David Rientjes <rientjes@...gle.com>,
        samba-technical@...ts.samba.org,
        virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        linux-sctp@...r.kernel.org, target-devel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
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        linux-scsi@...r.kernel.org, x86@...nel.org,
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Subject: Re: [PATCH 1/2] mm, treewide: Rename kzfree() to kfree_sensitive()

On 6/15/20 2:07 PM, Dan Carpenter wrote:
> On Mon, Apr 13, 2020 at 05:15:49PM -0400, Waiman Long wrote:
>> diff --git a/mm/slab_common.c b/mm/slab_common.c
>> index 23c7500eea7d..c08bc7eb20bd 100644
>> --- a/mm/slab_common.c
>> +++ b/mm/slab_common.c
>> @@ -1707,17 +1707,17 @@ void *krealloc(const void *p, size_t new_size, gfp_t flags)
>>   EXPORT_SYMBOL(krealloc);
>>   
>>   /**
>> - * kzfree - like kfree but zero memory
>> + * kfree_sensitive - Clear sensitive information in memory before freeing
>>    * @p: object to free memory of
>>    *
>>    * The memory of the object @p points to is zeroed before freed.
>> - * If @p is %NULL, kzfree() does nothing.
>> + * If @p is %NULL, kfree_sensitive() does nothing.
>>    *
>>    * Note: this function zeroes the whole allocated buffer which can be a good
>>    * deal bigger than the requested buffer size passed to kmalloc(). So be
>>    * careful when using this function in performance sensitive code.
>>    */
>> -void kzfree(const void *p)
>> +void kfree_sensitive(const void *p)
>>   {
>>   	size_t ks;
>>   	void *mem = (void *)p;
>> @@ -1725,10 +1725,10 @@ void kzfree(const void *p)
>>   	if (unlikely(ZERO_OR_NULL_PTR(mem)))
>>   		return;
>>   	ks = ksize(mem);
>> -	memset(mem, 0, ks);
>> +	memzero_explicit(mem, ks);
>          ^^^^^^^^^^^^^^^^^^^^^^^^^
> This is an unrelated bug fix.  It really needs to be pulled into a
> separate patch by itself and back ported to stable kernels.
>
>>   	kfree(mem);
>>   }
>> -EXPORT_SYMBOL(kzfree);
>> +EXPORT_SYMBOL(kfree_sensitive);
>>   
>>   /**
>>    * ksize - get the actual amount of memory allocated for a given object
> regards,
> dan carpenter
>
Thanks for the suggestion. I will break it out and post a version soon.

Cheers,
Longman