linux-kernel - Re: [PATCH] virtio-blk: allow toggling host cache between writeback and writethrough

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4FF53824.6090303@redhat.com>
Date:	Thu, 05 Jul 2012 08:45:56 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
CC:	linux-kernel@...r.kernel.org, rusty@...tcorp.com.au,
	kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH] virtio-blk: allow toggling host cache between writeback
 and writethrough

Il 04/07/2012 23:30, Michael S. Tsirkin ha scritto:
>>>>>> +static int virtblk_get_cache_mode(struct virtio_device *vdev)
>>>>>
>>>>> Why are you converting u8 to int here?
>>>>
>>>> The fact that it is a u8 is really an internal detail.  Perhaps the bug
>>>> is using u8 in the callers.
>>>
>>> Make it bool then?
>>>
>>> You are using u8 in the config. So you could get any value
>>> besides 0 and 1, and you interpret that as 1.
>>> Is 1 always a safe value? If not maybe it's better to set
>>> to a safe value if it is not 0 or 1, that is we don't know how to interpret it.
>>
>> That would be a host bug; the spec only gives meaning to 0 and 1.
> 
> Yes but if the other side does not validate values implementations
> *will* have bugs. Why not declare bits 1-7 reserved?

Ok, that would be a different change.  I thought about it yesterday, but
it seemed like a useless complication.  It's not like we have been
adding configuration fields every other week. :)

But I can certainly prepare patches to both virtio-blk and the spec for
that if you prefer.

Paolo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/