Re: [Qemu-devel] [PATCH for-3.1] vfio-helpers: Fix qemu_vfio_open_pci() crash

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 27 Nov 2018 09:41:43 +0100
Markus Armbruster <armbru@redhat.com> wrote:

> qemu_vfio_open_common() initializes s->lock only after passing s to
> qemu_vfio_dma_map() via qemu_vfio_init_ramblock().
> qemu_vfio_dma_map() tries to lock the uninitialized lock and crashes.
> 
> Fix by initializing s->lock first.
> 
> RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1645840
> Fixes: 418026ca43bc2626db092d7558258f9594366f28
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
> Compile-tested only, as I lack suitable hardware.  Cong Li (cc'ed) is
> going to test it for real.  It looks obvious enough to me to put it
> into -rc3 without waiting for the test results.  We can also wait and
> put it into -rc4.

This looks obvious to me as well.

> 
>  util/vfio-helpers.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
> index 1d9272efa4..cccc9cd42e 100644
> --- a/util/vfio-helpers.c
> +++ b/util/vfio-helpers.c
> @@ -411,13 +411,13 @@ static int qemu_vfio_init_ramblock(const char *block_name, void *host_addr,
>  
>  static void qemu_vfio_open_common(QEMUVFIOState *s)
>  {
> +    qemu_mutex_init(&s->lock);
>      s->ram_notifier.ram_block_added = qemu_vfio_ram_block_added;
>      s->ram_notifier.ram_block_removed = qemu_vfio_ram_block_removed;
>      ram_block_notifier_add(&s->ram_notifier);
>      s->low_water_mark = QEMU_VFIO_IOVA_MIN;
>      s->high_water_mark = QEMU_VFIO_IOVA_MAX;
>      qemu_ram_foreach_block(qemu_vfio_init_ramblock, s);
> -    qemu_mutex_init(&s->lock);
>  }
>  
>  /**

Reviewed-by: Cornelia Huck <cohuck@redhat.com>