From: Rusty Russell <rusty@rustcorp.com.au>
To: Cornelia Huck <cornelia.huck@de.ibm.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Cc: linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH] virtio: Don't access index after unregister.
Date: Fri, 09 Nov 2012 14:54:50 +1030 [thread overview]
Message-ID: <877gpv2yjx.fsf@rustcorp.com.au> (raw)
In-Reply-To: <1352371427-32363-1-git-send-email-cornelia.huck@de.ibm.com>
Cornelia Huck <cornelia.huck@de.ibm.com> writes:
> Virtio wants to release used indices after the corresponding
> virtio device has been unregistered. However, virtio does not
> hold an extra reference, giving up its last reference with
> device_unregister(), making accessing dev->index afterwards
> invalid.
>
> I actually saw problems when testing my (not-yet-merged)
> virtio-ccw code:
>
> - device_add virtio-net,id=xxx
> -> creates device virtio<n> with n>0
>
> - device_del xxx
> -> deletes virtio<n>, but calls ida_simple_remove with an
> index of 0
>
> - device_add virtio-net,id=xxx
> -> tries to add virtio0, which is still in use...
>
> So let's save the index we want to release before calling
> device_unregister().
Great catch! I've add a CC:stable.
Applied,
Rusty.
WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Cornelia Huck <cornelia.huck@de.ibm.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] virtio: Don't access index after unregister.
Date: Fri, 09 Nov 2012 14:54:50 +1030 [thread overview]
Message-ID: <877gpv2yjx.fsf@rustcorp.com.au> (raw)
In-Reply-To: <1352371427-32363-1-git-send-email-cornelia.huck@de.ibm.com>
Cornelia Huck <cornelia.huck@de.ibm.com> writes:
> Virtio wants to release used indices after the corresponding
> virtio device has been unregistered. However, virtio does not
> hold an extra reference, giving up its last reference with
> device_unregister(), making accessing dev->index afterwards
> invalid.
>
> I actually saw problems when testing my (not-yet-merged)
> virtio-ccw code:
>
> - device_add virtio-net,id=xxx
> -> creates device virtio<n> with n>0
>
> - device_del xxx
> -> deletes virtio<n>, but calls ida_simple_remove with an
> index of 0
>
> - device_add virtio-net,id=xxx
> -> tries to add virtio0, which is still in use...
>
> So let's save the index we want to release before calling
> device_unregister().
Great catch! I've add a CC:stable.
Applied,
Rusty.
next prev parent reply other threads:[~2012-11-09 4:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-08 10:43 [PATCH] virtio: Don't access index after unregister Cornelia Huck
2012-11-08 10:43 ` Cornelia Huck
2012-11-08 11:50 ` Sjur Brændeland
2012-11-08 11:50 ` Sjur Brændeland
2012-11-09 4:24 ` Rusty Russell [this message]
2012-11-09 4:24 ` Rusty Russell
2012-11-09 5:14 ` Michael S. Tsirkin
2012-11-09 5:14 ` Michael S. Tsirkin
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