netdev - Re: [PATCH net] ptr_ring: fail early if queue occupies more than KMALLOC_MAX

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Date:   Thu, 8 Feb 2018 11:04:18 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH net] ptr_ring: fail early if queue occupies more than
 KMALLOC_MAX_SIZE



On 2018年02月07日 23:15, Michael S. Tsirkin wrote:
> On Wed, Feb 07, 2018 at 05:17:59PM +0800, Jason Wang wrote:
>>
>> On 2018年02月07日 16:08, Jason Wang wrote:
>>> To avoid slab to warn about exceeded size, fail early if queue
>>> occupies more than KMALLOC_MAX_SIZE.
>>>
>>> Reported-by: syzbot+e4d4f9ddd4295539735d@...kaller.appspotmail.com
>>> Signed-off-by: Jason Wang <jasowang@...hat.com>
>>> ---
>>>    include/linux/ptr_ring.h | 2 ++
>>>    1 file changed, 2 insertions(+)
>>>
>>> diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
>>> index 1883d61..4b862da 100644
>>> --- a/include/linux/ptr_ring.h
>>> +++ b/include/linux/ptr_ring.h
>>> @@ -466,6 +466,8 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r,
>>>    static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)
>>>    {
>>> +	if (size > KMALLOC_MAX_SIZE)
>>> +		return NULL;
>>>    	return kcalloc(size, sizeof(void *), gfp);
>>>    }
>> Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
> That's probably not enough. How about switching to kvmalloc and limiting
> this drastically to e.g. 64K. I vaguely remember that some wise man said
> that should be enough for everybody :)
>

Okay, let me post a V2 to see if there's any objection.

Thanks