linux-kernel - Re: [PATCH 3/6] Protectable Memory

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Date:   Tue, 27 Mar 2018 14:43:19 +0300
From:   Igor Stoppa <igor.stoppa@...wei.com>
To:     Matthew Wilcox <willy@...radead.org>
CC:     <keescook@...omium.org>, <mhocko@...nel.org>,
        <david@...morbit.com>, <rppt@...ux.vnet.ibm.com>,
        <labbott@...hat.com>, <linux-security-module@...r.kernel.org>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <kernel-hardening@...ts.openwall.com>, <igor.stoppa@...il.com>
Subject: Re: [PATCH 3/6] Protectable Memory



On 27/03/18 05:31, Matthew Wilcox wrote:
> On Tue, Mar 27, 2018 at 04:55:21AM +0300, Igor Stoppa wrote:
>> +static inline void *pmalloc_array_align(struct pmalloc_pool *pool,
>> +					size_t n, size_t size,
>> +					short int align_order)
>> +{
> 
> You're missing:
> 
>         if (size != 0 && n > SIZE_MAX / size)
>                 return NULL;


ACK

>> +	return pmalloc_align(pool, n * size, align_order);
>> +}
> 
>> +static inline void *pcalloc_align(struct pmalloc_pool *pool, size_t n,
>> +				  size_t size, short int align_order)
>> +{
>> +	return pzalloc_align(pool, n * size, align_order);
>> +}
> 
> Ditto.

ok

>> +static inline void *pcalloc(struct pmalloc_pool *pool, size_t n,
>> +			    size_t size)
>> +{
>> +	return pzalloc_align(pool, n * size, PMALLOC_ALIGN_DEFAULT);
>> +}
> 
> If you make this one:
> 
> 	return pcalloc_align(pool, n, size, PMALLOC_ALIGN_DEFAULT)

ok

> then you don't need the check in this function.
> 
> Also, do we really need 'align' as a parameter to the allocator functions
> rather than to the pool?

I actually wrote it first without, but then I wondered how to deal if
one needs to allocate both small fry structures and then something
larger that is page aligned.

However it's just speculation, I do not have any real example.

> I'd just reuse ARCH_KMALLOC_MINALIGN from slab.h as the alignment, and
> then add the special alignment options when we have a real user for them.

ok

--
thanks, igor