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From: Sasha Levin <sasha.levin@oracle.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
	Sasha Levin <sasha.levin@oracle.com>
Cc: linux-kernel@vger.kernel.org, "open list:VIRTIO CORE,
	NET..." <virtualization@lists.linux-foundation.org>
Subject: Re: [PATCH 2/2] virtio: don't free memory until the underlying struct device has been released
Date: Sun, 04 Jan 2015 10:03:27 -0500	[thread overview]
Message-ID: <54A9563F.3070902@oracle.com> (raw)
In-Reply-To: <20150104112641.GB4336@redhat.com>

On 01/04/2015 06:26 AM, Michael S. Tsirkin wrote:
> On Fri, Jan 02, 2015 at 02:47:40PM -0500, Sasha Levin wrote:
>> > When releasing a virtio device, We can't free a struct virtio_device until the
>> > underlying struct device has been released, which might not happen immediately
>> > on device_unregister() even if that was the device's last reference.
>> > 
>> > Instead, free the memory only once we know the device is gone in the release
>> > callback.
>> > 
>> > Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> 
> Isn't this an old bug: do we need to copy stable on a fix?
> 
> What is the behaviour without this patch?
> Is there a way to make this cause a crash?

It will oops if CONFIG_DEBUG_KOBJECT_RELEASE is enabled. I guess
it needs to go to stable as well.


Thanks,
Sasha

WARNING: multiple messages have this Message-ID (diff)
From: Sasha Levin <sasha.levin@oracle.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
	Sasha Levin <sasha.levin@oracle.com>
Cc: linux-kernel@vger.kernel.org,
	Rusty Russell <rusty@rustcorp.com.au>,
	"open list:VIRTIO CORE,
	NET..."  <virtualization@lists.linux-foundation.org>
Subject: Re: [PATCH 2/2] virtio: don't free memory until the underlying struct device has been released
Date: Sun, 04 Jan 2015 10:03:27 -0500	[thread overview]
Message-ID: <54A9563F.3070902@oracle.com> (raw)
In-Reply-To: <20150104112641.GB4336@redhat.com>

On 01/04/2015 06:26 AM, Michael S. Tsirkin wrote:
> On Fri, Jan 02, 2015 at 02:47:40PM -0500, Sasha Levin wrote:
>> > When releasing a virtio device, We can't free a struct virtio_device until the
>> > underlying struct device has been released, which might not happen immediately
>> > on device_unregister() even if that was the device's last reference.
>> > 
>> > Instead, free the memory only once we know the device is gone in the release
>> > callback.
>> > 
>> > Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> 
> Isn't this an old bug: do we need to copy stable on a fix?
> 
> What is the behaviour without this patch?
> Is there a way to make this cause a crash?

It will oops if CONFIG_DEBUG_KOBJECT_RELEASE is enabled. I guess
it needs to go to stable as well.


Thanks,
Sasha


  reply	other threads:[~2015-01-04 15:03 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-02 19:47 [PATCH 1/2] virtio_pci: double free and invalid memory access of device vqs Sasha Levin
2015-01-02 19:47 ` Sasha Levin
2015-01-02 19:47 ` [PATCH 2/2] virtio: don't free memory until the underlying struct device has been released Sasha Levin
2015-01-02 19:47   ` Sasha Levin
2015-01-04 11:26   ` Michael S. Tsirkin
2015-01-04 11:26     ` Michael S. Tsirkin
2015-01-04 15:03     ` Sasha Levin [this message]
2015-01-04 15:03       ` Sasha Levin
2015-01-04 15:40       ` Michael S. Tsirkin
2015-01-04 15:40         ` Michael S. Tsirkin
2015-01-04 11:12 ` [PATCH 1/2] virtio_pci: double free and invalid memory access of device vqs Michael S. Tsirkin
2015-01-04 11:12   ` Michael S. Tsirkin

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