From: Coly Li <colyli@suse.de>
To: Ken Raeburn <raeburn@redhat.com>
Cc: linux-bcache@vger.kernel.org, linux-block@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH 1/2] bcache: avoid nr_stripes overflow in bcache_device_init()
Date: Mon, 13 Jul 2020 11:35:40 +0800 [thread overview]
Message-ID: <16edd3bb-944e-83fe-784c-35221f9ee287@suse.de> (raw)
In-Reply-To: <a504604d-ac8a-3276-e0b8-f42cb3782356@redhat.com>
On 2020/7/13 04:38, Ken Raeburn wrote:
>
> On 7/12/20 1:49 PM, Coly Li wrote:
>> On 2020/7/13 01:47, Coly Li wrote:
>>> For some block devices which large capacity (e.g. 8TB) but small io_opt
>>> size (e.g. 8 sectors), in bcache_device_init() the stripes number calcu-
>>> lated by,
>>> DIV_ROUND_UP_ULL(sectors, d->stripe_size);
>>> might be overflow to the unsigned int bcache_device->nr_stripes.
>>>
>>> This patch uses an unsigned long variable to store DIV_ROUND_UP_ULL()
>>> and after the value is checked to be available in unsigned int range,
>>> sets it to bache_device->nr_stripes. Then the overflow is avoided.
>> Hi Ken,
>>
>> Could you please to try whether these two patches may avoid the kernel
>> panic ? I will post the overwhelm stripe_size patch later.
>>
>> Thanks.
>>
>> Coly Li
>>
> I will. But, from inspection: On a 32-bit system, "unsigned long" will
> still be 32 bits, but sector_t (u64) will still be 64 bits, so that
> assignment will still discard high bits before validation in that
> environment. I suggest "unsigned long long" or another specifically
> 64-bit type.
>
> Also, the VDO driver I work on doesn't support 32-bit platforms
> currently, so my own testing will be limited to 64-bit platforms.
I will post a v2 for your test. Thanks :-)
Coly Li
next prev parent reply other threads:[~2020-07-13 3:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-12 17:47 [PATCH 1/2] bcache: avoid nr_stripes overflow in bcache_device_init() Coly Li
2020-07-12 17:47 ` [PATCH 2/2] bcche: fix overflow in offset_to_stripe() Coly Li
2020-07-17 17:08 ` Sasha Levin
2020-07-12 17:49 ` [PATCH 1/2] bcache: avoid nr_stripes overflow in bcache_device_init() Coly Li
2020-07-12 20:38 ` Ken Raeburn
2020-07-13 3:35 ` Coly Li [this message]
2020-07-12 20:37 ` Jens Axboe
2020-07-13 3:34 ` Coly Li
2020-07-17 17:08 ` Sasha Levin
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